Thinking of a number in particular? Find out if it is a prime number or if it is a composite number with prime factors.

Prime numbers are positive integers that can only be divided by themselves and 1. Apart from 2 all prime numbers are, by definition, odd numbers.

The first 10 prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29.

Some numbers are a composite of two or more prime numbers. For example, take 36 and 37. If we list the prime factors of 36, we have 2, 2, 3 and 3. If we list the factors of 37, we have only 37.

So we say that 37 is a prime number, but 36 is a composite number.

To determine whether a number is prime or composite, type a number in the box below and press 'Factors Of Number'.