Fait mathématique: 1784 is a number n for which f(n) is a repdigit.
Culture générale: 1784 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: November 18th is the day in 1686 that Charles Francois Felix operates on King Louis XIV of France's anal fistula after practicing the surgery on several peasants.