Fatto generale: 21048 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21048 is an uninteresting number.
Trivia: 21048 is an unremarkable number.
Data storica: August 16th is the day in 1891 that the Basilica of San Sebastian in Manila, the first all-steel church in Asia, is officially inaugurated and blessed.