Mathematical fact: 2056 is the magic constant of a 16×16 magic square.
Trivia: 2056 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Historical date: August 17th is the day in 986 that a Byzantine army is destroyed in the pass of Trajan's Gate by the Bulgarians under the Comitopuli Samuel and Aron.