Fatto generale: 21344 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21344 is an uninteresting number.
Trivia: 21344 is an uninteresting number.
Data storica: June 8th is the day in 1992 that the first World Ocean Day is celebrated, coinciding with the Earth Summit held in Rio de Janeiro, Brazil.