Fatto generale: 19861 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 19861 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 19861 is an uninteresting number.
Data storica: May 17th is the day in 1865 that the International Telegraph Union (later the International Telecommunication Union) is established in Paris.