Fait mathématique: 2616 is the number of graphs with 9 vertices and 6 cycles.
Culture générale: 2616 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: February 28th is the day in 1844 that a gun on USS Princeton explodes while the boat is on a Potomac River cruise, killing eight people, including two United States Cabinet members.