Fait mathématique: 9541 is a value of n for which n and 8n together use each digit 1-9 exactly once.
Culture générale: 9541 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: February 13th is the day in 1960 that Black college students stage the first of the Nashville sit-ins at three lunch counters in Nashville, Tennessee.