Fait général: 25857 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 25857 is a boring number.
Culture générale: 25857 is an unremarkable number.
Date historique: October 16th is the day in 1843 that Sir William Rowan Hamilton comes up with the idea of quaternions, a non-commutative extension of complex numbers.