Set of divisors function

Function

 definiendum $\mathrm{divisors}:\mathbb N^+\to\mathcal{P}(\mathbb N)$ definiendum $\mathrm{divisors}(n):=\{a\ |\ \exists (b\in\mathbb N).\ a\cdot b=n\}$
make this into a set

Code

A related Boolean function is

divides :: Integral a => a -> a -> Bool
divides d n = rem n d == 0