Il numero romano MMMDXCI nel sistema decimale vale: 3591.
MMMDXCI in latino si scrive tria milia quingenti nonaginta unus,
mentre in italiano tremilacinquecentonovantuno.
MMMDLXXII, MMMDLXXIII, MMMDLXXIV, MMMDLXXV, MMMDLXXVI, MMMDLXXVII, MMMDLXXVIII, MMMDLXXIX, MMMDLXXX, MMMDLXXXI, MMMDLXXXII, MMMDLXXXIII, MMMDLXXXIV, MMMDLXXXV, MMMDLXXXVI, MMMDLXXXVII, MMMDLXXXVIII, MMMDLXXXIX, MMMDXC, MMMDXCII, MMMDXCIII, MMMDXCIV, MMMDXCV, MMMDXCVI, MMMDXCVII, MMMDXCVIII, MMMDXCIX, MMMDC, MMMDCI, MMMDCII, MMMDCIII, MMMDCIV, MMMDCV, MMMDCVI, MMMDCVII, MMMDCVIII, MMMDCIX, MMMDCX