The Roman number MMMCCLXXV corresponds to the arabic number 3275.
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.
Fact: In astronomy, the natural satellites or “moons” of the planets are traditionally designated by capital Roman numerals appended to the planet’s name. For example, Titan’s designation is Saturn VI.