general_fact: 841 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 841 is a square that is also the sum of 2 consecutive squares.
trivia: 841 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
historical_date: April 20th is the day in 1535 that the Sun dog phenomenon observed over Stockholm and depicted in the famous painting "Vädersolstavlan".