Fatto generale: 83991 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 83991 is a boring number.
Trivia: 83991 is a boring number.
Data storica: December 16th is the day in 1930 that Bank robber Herman Lamm and members of his crew are killed by a posse of 200, following a botched bank robbery in Clinton, Indiana.