A prime number is any positive integer greater than zero that has only two proper divisorsA proper divisor is a number n that when divided into another number N leaves no remainder. , 1 and the number itself. Thus the lowest prime number is 2, which is also the only even prime;[a] numbers greater than 1 that are not prime are known as composite numbers, because they can be expressed as the product of two other numbers smaller than themselves;[1] for instance, 8 can be expressed as  2\times{4} . (The prime factor of 8 is  2^3 )

Prime numbers are fundamental to mathematics, as all whole numbers can be constructed from them; anything that can be shown to be true about prime numbers is therefore true for all numbers.[2]



Neale, V. (2017). Closing the Gap: The Quest to understand Prime Numbers (ebook). Oxford University Press.
Weisstein, E. W. (n.d.). Prime number. MathWorld. http://mathworld.wolfram.com/PrimeNumber.html


  1. One is not a prime number because it has only one proper divisor, itself.