Fait général: 2840 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 2840 is an uninteresting number.
Culture générale: 2840 is an unremarkable number.
Date historique: October 10th is the day in 1913 that President Woodrow Wilson triggers the explosion of the Gamboa Dike thus ending construction on the Panama Canal.