Fait général: 6991 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 6991 is a value of n for which reverse(f(n)) = f(reverse(n)).
Culture générale: 6991 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: February 20th is the day in 1472 that Orkney and Shetland are pawned by Norway to Scotland in lieu of a dowry for Margaret of Denmark.