general_fact: 21799 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 21799 is an unremarkable number.
trivia: 21799 is an uninteresting number.
historical_date: September 6th is the day in 1492 that Christopher Columbus sails from La Gomera in the Canary Islands, his final port of call before crossing the Atlantic for the first time.