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Prime Number and Composite Number

Find out what is a Prime Number and Composite Number? Find out if a number is prime number or composite number

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Prime Number


You can input a number and find if it is a prime number or composite number and the factors for the number.
1 is NOT A PRIME NUMBER.

Prime and Composite Numbers

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  • Prime Number Definition

    Prime numbers are positive numbers that can only divisible by itself or by 1.In other words, the number which has exactly two factors 1 and the number itself is said to be a Prime number.
    2 is a even prime number

  • Prime numbers 1 to 100

    2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.

  • Composite Number Definition

    Composite Numbers are positive numbers that has more than two factors.In other words which can be written as multiplication of two or three numbers.

  • Example of Composite Numbers from 1 to 100

    4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, 30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81,82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100.

Steps to find the number is prime or not.

User Guide icon
  • First method : Step 1

    First divide the number by smaller prime numbers 2 , 3, 5 and so on..If we get a whole number then it cant be a prime number.

  • Step 2

    If we dont get the whole number as a result of dividing the number by prime numbers, then it is prime number.

  • Example:

    Check 8 is a prime or not.
    Step 1: Divide 8 by 2 we get a result 4 and that is whole number so it fails to be a prime number.

    Check 7 is a prime or not.
    Step 1:Divide 7 by 2 we dont get whole number as result , repeat the process of dviding the number by next prime number 3 and still we dont get whole number as result again repeat by dividing 7 by 5 still it gives non whole number.since there is no factor before 7 we can conclude that 7 is a prime

  • Second method : Step 1

    Find all factors of the number

  • Step 2

    If the number has only two factors, then it is a prime otherwise it is composite number.

  • Example:

    Check 6 is a prime or not.
    Step 1: Factors of six are 1, 2, 3 and 6.Since it has factors more than two it is not a prime number.

What is Twin Prime?

User Guide icon
  • Definition of Twin Prime:

    Two prime numbers are said to twin prime if there difference is exactly two.

  • Example:

    (3,5) , (5,7) , (11,13) and so on..

  • Is (2,3) a twin prime?

    No, because two is a only even prime and their difference is not exactly two.

Table of Numbers - Is It Prime or Composite Number?

Conversion Table Icon

Number

Prime number or Composite number

Reason

0

Neither Prime nor Composite

Prime number has to be greater than 1.

1

1 is not a prime number

It has only one factor

2

2 is an even prime number

It has only two factors 1 and 2 itself.

3

3 is a prime number

It has only two factors 1 and 3 itself.

4

4 is a composite number

It has more than two factors.Factors are 1,2 4

5

5 is a prime number

It has only two factors.

6

6 is a composite number

It has 1,2,3,6 factors

7

7 is a prime number

it has only two factors 1 and itself

8

8 is a composite number

It has 1, 2, 4,8 as the factors

9

9 is a composite number

9 is divisible by 3.So it is not a prime

10

10 is a composite number

10 is divisible by 5

11

11 is a prime number

11 has no factors rather than 1 and 11

12

12 is a composite number

12 is divisible by 2 , 3 , 4 and 6 which is other than 1 and 12

13

13 is a prime number

13 has only two factors

14

14 is a composite number

14 is divisible by 2 and 7

15

15 is a composite number

15 = 3 x 5 and so it is composite number

16

16 is a composite number

16 = 2 x 8 it is a composite number

17

17 is a prime number

It has only two factors

18

18 is a composite number

18 can be written as multiplication of two number.

19

19 is a prime number

It has only two factors

20

20 is a composite number

20 can be written as 4 x 5

21

21 is a composite number

21 has 3 and 7 as factors rather than 1 and 21 itself

23

23 is a prime number

It has only two factors.

25

25 is a composite number

25 is a square of 5.

26

26 is a composite number

It has 13 and 2 as a factor

27

27 is a composite number

27 = 3 x 9 can be written as multiplication of two number.

29

29 is a prime number

It has only two factors

31

31 is a prime number

It has only two factors

32

32 is a composite number

32 = 8 x 4 written as multiplication of two numbers

33

33 is a composite number

factors are 11 and 3 rather than 1 and itself

34

34 is a composite number

It has more than two factors

36

36 is a composite number

It has more than two factors

37

37 is a prime number

It has only two factors

39

39 is a composite number

It has more than two factors

41

41 is a prime number

It has only two factors

43

43 is a prime number

It has only two factors

47

47 is a prime number

It has only two factors

51

51 is a composite number

It has more than two factors

57

57 is a composite number

It has more than two factors

59

59 is a prime number

It has only two factors

61

61 is a prime number

It has only two factors

67

67 is a prime number

It has only two factors

73

73 is a prime number

It has only two factors

75

75 is a composite number

It has more than two factors

79

79 is a prime number

It has only two factors

83

83 is a prime number

It has only two factors

87

87 is a composite number

3 and 29 are two factors

89

89 is a prime number

It has only two factors

93

93 is a composite number

93 can written as 21 x 3

97

97 is a prime number

It has only two factors

99

99 is a composite number

It has more than two factors

101

101 is a prime number

It has only two factors

103

103 is a prime number

It has only two factors

109

109 is a prime number

It has only two factors

111

111 is a composite number

111 = 37 x 3

119

119 is a composite number

119 = 17 x 7

123

123 is a composite number

3 is one of the factor

127

127 is a prime number

It has only two factors

131

131 is a prime number

It has only two factors

143

143 is a composite number

It has 11 as a factors

149

149 is a prime number

It has only two factors

599

599 is a prime number

It has only two factors

601

601 is a prime number

It has only two factors

610

610 is a composite number

It has more than two factors

1325

1325 is a composite number

It has more than two factors

1999

1999 is a prime number

It has only two factors

2001

2001 is a composite number

It has 3 as a factors

2027

2027 is a prime number

It has only two factors

9973

9973 is a prime number

It has only two factors

9999

9999 is a composite number

9 and 11 are the factors rather than 1 and 9999

Frequently Asked Questions on Prime Number and Composite Number

FAQ icon

  • Prime numbers are positive numbers that can only divisible by itself or by 1.
    In other words, the number which has exactly two factors 1 and the number itself is said to be a Prime number.

  • Composite Numbers are positive numbers that has more than two factors.In other words which can be written as multiplication of two or three numbers.

  • Prime number is not divisible by any number other than 1 and the number itself.Prime number has only two factors. Composite number is divisible by other number rather than 1 and the number itself.Composite number has more than two factors.

  • Two prime numbers are said to be twin prime if there differece is exactly two.

  • Number 2 is the first and lowest prime number.And it is also known as even prime.

  • The largest known prime number (as of May 2022) is 2 to the power of 82,589,933 − 1, a number which has 24,862,048 digits when written in base 10.
    According to Euclid's theorem there are infinitely many prime numbers, so there is no largest prime.

  • 2 is the first and lowest prime number.

  • 2 is the only even prime number

  • No, 1 is not a prime nor a composite number.

  • No, 0 is not a prime nor a composite number. Because 0 is considered to be a neutral number.A number to be a prime it has to be greater than 1 and so 0 is not.

  • 2 is a prime number because it has exactly two factors 1 and 2.

  • First divide the number by smaller prime numbers 2 , 3, 5 and so on..If we get a whole number then it cant be a prime number.

  • If we dont get the whole number as a result of dividing the number by prime numbers, then it is prime number.