math_fact: 81180 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
trivia: 81180 is an uninteresting number.
historical_date: April 6th is the day in 46 BC that Julius Caesar defeats Caecilius Metellus Scipio and Marcus Porcius Cato (Cato the Younger) in the battle of Thapsus.