Basic College Mathematics (10th Edition)

Prime numbers are defined as (a) whole and (b) only divisible (evenly) by themselves and 1. For example, the numbers $3$, $5$, and $7$ are prime because they have no factor aside from themselves and 1. Composite numbers are the "opposite" of prime numbers. That is, they have more factors than just themselves and 1. For example, even numbers (aside from 2) are composite; e.g. $4$, $6$, and $8$. The numbers $0$ and $1$ are neither prime nor composite.