Hecho general: 1606 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 1606 is the number of strongly connected digraphs with 4 vertices.
Trivia: 1606 is an uninteresting number.
Fecha histórica: May 24th is the day in 1958 that United Press International is formed through a merger of the United Press and the International News Service.