general_fact: 20818 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 20818 is a boring number.
trivia: 20818 is an uninteresting number.
historical_date: December 29th is the day in 1911 that Sun Yat-sen becomes the provisional President of the Republic of China; he formally takes office on January 1, 1912.