Fait mathématique: 4311 is the largest number n known with the property that n-2^{k} is a pseudoprime for all k>0.
Culture générale: 4311 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: October 20th is the day in 1976 that the ferry George Prince is struck by a ship while crossing the Mississippi River between Destrehan and Luling, Louisiana.