math_fact: 20820 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
trivia: 20820 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: December 31st is the day in 1790 that Efimeris, the oldest Greek newspaper of which issues have survived till today is published for the first time.