Fait mathématique: 12866 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Culture générale: 12866 is an unremarkable number.
Date historique: March 23rd is the day in 1801 that Tsar Paul I of Russia is struck with a sword, then strangled, and finally trampled to death in his bedroom at St. Michael's Castle.