Fatto generale: 1546 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 1546 is the number of 5×5 binary matrices with at most one 1 in each row and column.
Trivia: 1546 is an unremarkable number.
Data storica: March 25th is the day in 1957 that the European Economic Community is established (West Germany, France, Italy, Belgium, Netherlands, Luxembourg).