Hecho matemático: 21018 is an unremarkable number.
Trivia: 21018 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
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.