Fait général: 1525 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 1525 is a value of n for which s(f(n)) = 2s(n).
Culture générale: 1525 is an unremarkable number.
Date historique: March 4th is the day in 1996 that a derailed train in Weyauwega, Wisconsin, US, causes the emergency evacuation of 2,300 people for 16 days.