General fact: 5821 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 5821 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 5821 is an unremarkable number.
Historical date: December 8th is the day in 1972 that United Airlines Flight 553 crashes after aborting its landing attempt at Chicago Midway International Airport, killing 45.