Prime factor

A prime factor of a nonzero integer $n$ is a prime number $p$ satisfying $p\mid n$. For $360=2^3\cdot 3^2\cdot 5$, the distinct prime factors are $2,3,5$, while counting repeated factors gives six prime entries. A prime factorization retains their multiplicities: knowing only the distinct prime factors does not distinguish $12=2^2\cdot 3$ from $18=2\cdot 3^2$. A negative integer has the same prime factors as its absolute value.