A prime number is any number whose only factors are 1 and itself.

Contrast composite numbers with composite numbers.

### Some often-confused facts about prime numbers

- 0, zero, is
**not**a prime a number - 1 is also
**not**a prime number. Although the definition of a prime number seems to apply to 1, you have to count 1 twice --sorry no 'double dipping' for prime numbers. 1 is not prime. - 2 : The only even prime number is 2, because all of the other even prime numbers are multiples of 2 and therefore violate the definition of a prime number (only divisible by 1 and itself)
- Read more about how to determine if a number is prime