General fact: 36521 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 36521 is an uninteresting number.
Trivia: 36521 is an unremarkable number.
Historical date: December 28th is the day in 1972 that Kim Il-sung, already Prime Minister of North Korea and General Secretary of the Workers' Party of Korea, became the first President of North Korea.