Fatto matematico: 15689 is an unremarkable number.
Trivia: 15689 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: December 14th is the day in 1913 that Haruna, the fourth and last ship of the Kongō-class, launches, eventually becoming one of the Japanese workhorses during World War I and World War II.