365 (three hundred [and] sixty-five) is the natural number following 364 and preceding 366.
365 is a semiprime centered square number.
It is the smallest number that has more than one expression as a sum of consecutive square numbers: There are no known primes with period 365, while at least one prime with each of the periods 1 to 364 is known.
[1] Related to this, in Ontario, the driver's license learner's permit used to be called "365"[2][3] because it was valid for only 366 days.
Financial and scientific calculations often use a 365-day calendar to simplify daily rates.