General fact: 8391 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 8391 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 8391 is a boring number.
Historical date: December 21st is the day in 1826 that American settlers in Nacogdoches, Mexican Texas, declare their independence, starting the Fredonian Rebellion.