Fait mathématique: 2806 is the number of semigroups of order 6 with 2 idempotents.
Culture générale: 2806 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: September 6th is the day in 1943 that the Monterrey Institute of Technology, one of the largest and most influential private universities in Latin America, is founded in Monterrey, Mexico.