Hecho general: 564 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 564 is the number of 13-ominoes with a horizontal or vertical line of symmetry.
Trivia: 564 is a boring number.
Fecha histórica: July 17th is the day in 1981 that a structural failure leads to the collapse of a walkway at the Hyatt Regency in Kansas City, Missouri killing 114 people and injuring more than 200.