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 1940 that New York City's "Mad Bomber" George Metesky places his first bomb at a Manhattan office building used by Consolidated Edison.