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 unremarkable number.
Trivia: 21048 is an uninteresting number.
Data storica: August 16th is the day in 1927 that the Dole Air Race begins from Oakland, California, to Honolulu, Hawaii, during which six out of the eight participating planes crash or disappear.