math_fact: 2291 is the number of inequivalent Ferrers graphs with 29 points.
trivia: 2291 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: April 9th is the day in 1937 that the Kamikaze arrives at Croydon Airport in London – it is the first Japanese-built aircraft to fly to Europe.