mathlib3

c2337ec8 - chore(number_theory/divisors): golf (#17954)

chore(number_theory/divisors): golf (#17954) * Upgrade `nat.swap_mem_divisors_antidiagonal` to a `simp` `iff` lemma. * Use `(equiv.prod_comm _ _).to_embedding` instead of `⟨prod.swap, _⟩`. * Golf.