An integer greater than 1 is prime if its only positive integer divisors are 1 and itself. Otherwise, it is composite. Prime numbers are central elements of number theory, established as such by the fundamental theorem of arithmetic, which recognizes that all integers greater than 1 can be decomposed into unique products of primes. Wolfram|Alpha has many tools for working with primes and related ideas.
Check numbers for primality. Generate prime numbers or lists of prime numbers meeting certain conditions.
Work with special subsets of prime numbers. Find numbers within these sets or check for membership.
Decompose numbers into products of primes, which are unique per the fundamental theorem of arithmetic.