math_fact: 21441 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
trivia: 21441 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: September 13th is the day in 1899 that Mackinder, Ollier and Brocherel make the first ascent of Batian (5,199 m – 17,058 ft), the highest peak of Mount Kenya.