Set of divisors 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

A related Boolean function is

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