general_fact: 47231 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 47231 is an unremarkable number.
trivia: 47231 is a boring number.
historical_date: April 24th is the day in 1918 that First tank-to-tank combat, at Villers-Bretonneux, France, when three British Mark IVs met three German A7Vs.