Fait général: 6816 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 6816 is the index of a triangular number containing only 3 different digits.
Culture générale: 6816 is an unremarkable number.
Date historique: August 29th is the day in 1996 that Vnukovo Airlines Flight 2801, a Vnukovo Airlines Tupolev Tu-154, crashes into a mountain on the Arctic island of Spitsbergen, killing all 141 aboard.