Il numero romano MMMMDXCI nel sistema decimale vale: 4591.
MMMMDXCI in latino si scrive quattuor milia quingenti nonaginta unus,
mentre in italiano quattromilacinquecentonovantuno.
MMMMDLXXII, MMMMDLXXIII, MMMMDLXXIV, MMMMDLXXV, MMMMDLXXVI, MMMMDLXXVII, MMMMDLXXVIII, MMMMDLXXIX, MMMMDLXXX, MMMMDLXXXI, MMMMDLXXXII, MMMMDLXXXIII, MMMMDLXXXIV, MMMMDLXXXV, MMMMDLXXXVI, MMMMDLXXXVII, MMMMDLXXXVIII, MMMMDLXXXIX, MMMMDXC, MMMMDXCII, MMMMDXCIII, MMMMDXCIV, MMMMDXCV, MMMMDXCVI, MMMMDXCVII, MMMMDXCVIII, MMMMDXCIX, MMMMDC, MMMMDCI, MMMMDCII, MMMMDCIII, MMMMDCIV, MMMMDCV, MMMMDCVI, MMMMDCVII, MMMMDCVIII, MMMMDCIX, MMMMDCX