general_fact: 11539 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 11539 is an uninteresting number.
trivia: 11539 is a boring number.
historical_date: August 4th is the day in 1863 that Matica slovenská, Slovakia's public-law cultural and scientific institution focusing on topics around the Slovak nation, is established in Martin.