# Prime Number and Composite Number

## Find out if a number is prime number or composite number

HomeMath

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

• 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.

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?

• 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?

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

• 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.