Fait mathématique: 2120 is the number of ways to stack 16 pennies in a line so that each penny lies on the table or on two pennies.
Culture générale: 2120 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 1944 that Liquid natural gas leaks from storage tanks in Cleveland, then explodes; the explosion and resulting fire level 30 blocks and kill 130.