Fait général: 21477 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 21477 is an uninteresting number.
Culture générale: 21477 is an uninteresting number.
Date historique: October 19th is the day in 1866 that Venice - Annexion of Veneto and Mantua to Italy - At Hotel Europa, Austria hands over Veneto to France, which hands it immediately over to Italy.