Fatto generale: 21874 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21874 is an unremarkable number.
Trivia: 21874 is a boring number.
Data storica: November 20th is the day in 1739 that Start of the Battle of Porto Bello between British and Spanish forces during the War of Jenkins' Ear.