Pretty much anything. If you want it to come out evenly, try 1,3,5 or 15.
18
1.4667
9.6667
15 divided by one is 15. Anything divided by one is that same thing. One is the identity.
37.5 divided by 2.5 = 15
148
15 divided by 5 is 3 and 15 divided by 3 is 5
23.8
15 is the highest number 15 can be divided by evenly.
10.6667
59
9.7333