Fait général: 15515 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 15515 is a boring number.
Culture générale: 15515 is an unremarkable number.
Date historique: June 23rd is the day in 1985 that a terrorist bomb aboard Air India flight 182 brings the Boeing 747 down off the coast of Ireland killing all 329 aboard.