Chapter 7.1, Problem 1E

In Problems 1-6, refer to the footnote for the definitions of divisors, multiple, prime, even, and odd.*

List the positive integers that are divisors of $20$.

*An integer $d$ is a divisor of an integer $n$ (and $n$ is a multiple of $d$ ) if $n=kd$ for some integer for some integer $k$. An integer $n$ is even if $2$ is a divisor of $n$ ; otherwise, $n$ is odd. An integer $p>1$ is prime if its only positive divisors are $1$ and $p$.