General fact: 21977 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 21977 is an unremarkable number.
Trivia: 21977 is an uninteresting number.
Historical date: March 2nd is the day in 1825 that Roberto Cofresí, one of the last successful Caribbean pirates, is defeated in combat and captured by authorities.