Fatto generale: 21479 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21479 is an unremarkable number.
Trivia: 21479 is an uninteresting number.
Data storica: October 21st is the day in 1520 that João Álvares Fagundes discovers the islands of Saint-Pierre and Miquelon, bestowing them their original name of "Islands of the 11,000 Virgins".