Fait général: 11581 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 11581 is an unremarkable number.
Culture générale: 11581 is an uninteresting number.
Date historique: September 15th is the day in 1962 that the Soviet ship Poltava heads toward Cuba, one of the events that sets into motion the Cuban Missile Crisis.