general_fact: 2421 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 2421 is a boring number.
trivia: 2421 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: August 17th is the day in 2008 that American swimmer Michael Phelps becomes the first person to win eight gold medals in one Olympic Games.