17

 17 is the seventh prime number.

17 is the third Fermat number 17 = +1

17 is equal to the sum of the digits of its cube 4913

17 is the first sum of two distinct 4th powers: 17 = 1⁴ + 2⁴

There are 17 essentially different symmetry patterns for a wallpaper design.

It is possible to construct a regular 17 sided polygon using ruler and compasses only.