Fait général: 21751 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 21751 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Culture générale: 21751 is an unremarkable number.
Date historique: July 20th is the day in 1969 that a cease fire is announced between Honduras and El Salvador, 6 days after the beginning of the "Football War".