36mn + 63m - n =

36mn + 63m - n can be factored a bit:

• Factor out 9m from the first two terms: 9m(4n + 7) - n.

So a convenient form is: 9m(4n + 7) - n.

(Equivalently: n(36m − 1) + 63m. No further simple factoring into a product is possible over the integers.)