Fatto generale: 99521 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 99521 is an unremarkable number.
Trivia: 99521 is a boring number.
Data storica: June 23rd is the day in 1894 that the International Olympic Committee is founded at the Sorbonne in Paris, at the initiative of Baron Pierre de Coubertin.