Fatto generale: 21803 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21803 is a boring number.
Trivia: 21803 is a boring number.
Data storica: September 10th is the day in 2001 that Charles Ingram cheats his way into winning one million pounds on a British version of Who Wants to be a Millionaire.