general_fact: 21435 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 21435 is an unremarkable number.
trivia: 21435 is a boring number.
historical_date: September 7th is the day in 1895 that the first game of what would become known as rugby league football is played, in England, starting the 1895–96 Northern Rugby Football Union season.