math_fact: 1521 is the smallest number that can be written as the sum of 4 distinct cubes in 3 ways.
trivia: 1521 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: February 29th is the day in 1960 that an earthquake in Morocco kills over 3,000 people and nearly destroys Agadir in the southern part of the country.