Hecho general: 5559 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 5559 is an uninteresting number.
Trivia: 5559 is an unremarkable number.
Fecha histórica: March 21st is the day in 1919 that the Hungarian Soviet Republic is established becoming the first Communist government to be formed in Europe after the October Revolution in Russia.