Fatto generale: 243 is the Calling code for Zaire.
Fatto matematico: 243 is a perfect totient number.
Trivia: 243 is the number of Earth Days for the planet Venus to complete one Venetian day, one revolution.
Data storica: August 30th is the day in 1974 that a Belgrade–Dortmund express train derails at the main train station in Zagreb killing 153 passengers.