general_fact: 21490 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 21490 is an unremarkable number.
trivia: 21490 is an uninteresting number.
historical_date: November 1st is the day in 1790 that Edmund Burke publishes Reflections on the Revolution in France, in which he predicts that the French Revolution will end in a disaster.