Fait mathématique: 21879 is an uninteresting number.
Culture générale: 21879 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: November 25th is the day in 1833 that a massive undersea earthquake, estimated magnitude between 8.7-9.2 rocks Sumatra, producing a massive tsunami all along the Indonesian coast.