general_fact: 19813 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 19813 is a boring number.
trivia: 19813 is an unremarkable number.
historical_date: March 30th is the day in 1867 that Alaska is purchased from Russia for $7.2 million, about 2 cent/acre ($4.19/km²), by United States Secretary of State William H. Seward.