Fait mathématique: 2176 is the number of prime knots with 12 crossings.
Culture générale: 2176 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: December 15th is the day in 1256 that Hulagu Khan captures and destroys the Hashshashin stronghold at Alamut in present-day Iran as part of the Mongol offensive on Islamic southwest Asia.