The Roman number MMMCXLVII corresponds to the arabic number 3147.
There is no common alternative notation for this number.
You are looking for acronyms beginning with MM? Here is our list with acronyms starting with MM.
Interesting Fact: In the French Republican Calendar, initiated during the French Revolution, years were numbered by Roman numerals – from the year I (1792) when this calendar was introduced to the year XIV (1805) when it was abandoned.