1 and 13.
Itself and any of its multiples
1, 13, 169.
13
4 goes into 36 evenly, but 13 does not.
1, 13, 487, 6331.
Just the number one.
1, 3, 13, 39
1, 13, 37, 481.
1/13 is the highest number
1, 3, 13, 39.
1, 11, 13, 143.
Each of these numbers will go evenly into 91: 1, 7, 13, 91.