Fait général: 21858 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 21858 is an unremarkable number.
Culture générale: 21858 is a boring number.
Date historique: November 4th is the day in 1791 that the Western Confederacy of American Indians wins a major victory over the United States in the Battle of the Wabash.