669

669 = 3 x 223.

669 is the number of unsymmetrical ways to dissect a regular 12-gon into 10 triangles.

669 is 3033 in base 6 and 1235 in base 8.

669 is the number of primes less than 5,000.

NGC 669 is a galaxy in the constellation Triangulum.

Source: What's Special About This Number?