Prime factorisation

Prime factorisation is the expression of a positive integer as a product of prime numbers.

For example, $60=2^2\times3\times5$. The Fundamental Theorem of Arithmetic says that, apart from ordering, this prime factorisation is unique. That unique multiplicative structure is one reason primes play such a central role in number theory.

See also: prime number, Fundamental Theorem of Arithmetic, prime power..