general_fact: 2391 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 2391 is the number of ways to flip a coin 12 times and get at least 3 heads in a row.
trivia: 2391 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: July 18th is the day in 1555 that the College of Arms was reincorporated by Royal Charter signed by Queen Mary I of England and King Philip II of Spain.