math_fact: 2806 is the number of semigroups of order 6 with 2 idempotents.
trivia: 2806 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: September 6th is the day in 1991 that the name Saint Petersburg is restored to Russia's second largest city, which had been renamed Leningrad in 1924.