Fait mathématique: 9751 is the number of possible configurations of pegs (up to symmetry) after 8 jumps in solitaire.
Culture générale: 9751 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: September 11th is the day in 1226 that the Roman Catholic practice of public adoration of the Blessed Sacrament outside of Mass spreads from monasteries to parishes.