Fatto generale: 21133 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21133 is an unremarkable number.
Trivia: 21133 is a boring number.
Data storica: November 9th is the day in 1913 that the Great Lakes Storm of 1913, the most destructive natural disaster ever to hit the lakes, destroys 19 ships and kills more than 250 people.