Fait général: 18891 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 18891 is an uninteresting number.
Culture générale: 18891 is a boring number.
Date historique: September 20th is the day in 1973 that Billie Jean King beats Bobby Riggs in The Battle of the Sexes tennis match at the Houston Astrodome in Houston, Texas.