Fatto generale: 18213 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 18213 is a boring number.
Trivia: 18213 is an uninteresting number.
Data storica: November 11th is the day in 1865 that Treaty of Sinchula is signed by which Bhutan cedes the areas east of the Teesta River to the British East India Company.