Fatto generale: 21117 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21117 is an unremarkable number.
Trivia: 21117 is an unremarkable number.
Data storica: October 24th is the day in 1930 that a bloodless coup d'état in Brazil ousts Washington Luís Pereira de Sousa, the last President of the First Republic.