Fatto generale: 618 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 618 is the number of ternary square-free words of length 15.
Trivia: 618 is an uninteresting number.
Data storica: September 9th is the day in 1543 that Mary Stuart, at nine months old, is crowned "Queen of Scots" in the central Scottish town of Stirling.