Hecho general: 6564 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 6564 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 6564 is an uninteresting number.
Fecha histórica: December 20th is the day in 1988 that the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances is signed in Vienna.