365

365 = 5 x 73.

365 is 101101101 in base 2 (binary). It is 555 in base 8.

365 is a centered square number and a centered tridecagonal number (A051865).

365 is the smallest number that can be written as a sum of consecutive squares in more than one way: 365 = 14² + 13² = 12² + 11² + 10².

365 has two representations as a sum of two squares: 365 = 2² + 19² = 13² + 14².

365 is the hypotenuse of two primitive Pythagorean triples: 365² = 27² + 364² = 76² + 357².

365 is the most frequent number of days in a year.

Source: What's Special About This Number?