Fait mathématique: 1257 is a value of n for which f(s(n)) = f(n).
Culture générale: 1257 is an unremarkable number.
Date historique: June 10th is the day in 1786 that a landslide dam on the Dadu River created by an earthquake ten days earlier collapses, killing 100,000 in the Sichuan province of China.