Fatto generale: 7917 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 7917 is the number of partitions of 57 into distinct parts.
Trivia: 7917 is an unremarkable number.
Data storica: September 3rd is the day in 1874 that the congress of the state of México elevates Naucalpan to the category of Villa, with the title of "Villa de Juárez".