general_fact: 9615 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 9615 is the smallest number whose cube starts with 5 identical digits.
trivia: 9615 is a boring number.
historical_date: April 28th is the day in 1792 that France invades the Austrian Netherlands (present day Belgium), beginning the French Revolutionary War.