Notation: is a factor of

Question

How can one write $x$ is a factor of $y$ (as a constraint)? I am also not sure what else to add to meet the question quality requirements.

Answer 1

$x$ is a factor of $y$ is the same thing as $y$ is a multiple of $x$. You can write

$$y=kx \ \text{ for some integer $k$}$$

Answer 2

Well $|$ is used to describe divisibility so I think it meets our requirements.

For example, $3|6$.

$x$ is a factor of $y$ $\Leftrightarrow$ $x|y$.