Prime number/Citable Version

A prime number is a whole number (i.e, one having no fractional or decimal part) that cannot be evenly divided by any numbers but $1$ and itself. The first few prime numbers are $2$, $3$, $5$, $7$, $11$, $13$, and so on. With the exception of $2$, the first few numbers on this list are odd numbers, but not every odd number is prime. For example, $9=3\cdot 3$ and $15=3\cdot 5$, so neither $9$ nor $15$ is prime.