Fait général: 20015 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 20015 is an unremarkable number.
Culture générale: 20015 is an unremarkable number.
Date historique: October 18th is the day in 1356 that Basel earthquake, the most significant historic seismological event north of the Alps, destroys the town of Basel, Switzerland.