Prime Number definition, examples

Definition: A prime number is a number whose only factors are 1 and itself. That means there is no whole number that evenly divides the prime number.

Some often-confused facts about prime numbers

  • Zero is not a prime a number
  • The number one, 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.
  • 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