652

652 = 2² x 163. It is a power of 2 written backwards.

652 has a unique representation as a sum of three squares: 652 = 2² + 18² + 18².

652 is the maximum number of regions into which 26 circles can divide the plane.

652 is the only known non-perfect number whose number of divisors and sum of smaller divisors are perfect.

652 is 220011 in base 3. It is 543 in base 11, 464 in base 12, and 246 in base 18.

Source: What's Special About This Number?