Il numero romano MMMMCDXCI nel sistema decimale vale: 4491.
MMMMCDXCI in latino si scrive quattuor milia quadringenti nonaginta unus,
mentre in italiano quattromilaquattrocentonovantuno.
MMMMCDLXXII, MMMMCDLXXIII, MMMMCDLXXIV, MMMMCDLXXV, MMMMCDLXXVI, MMMMCDLXXVII, MMMMCDLXXVIII, MMMMCDLXXIX, MMMMCDLXXX, MMMMCDLXXXI, MMMMCDLXXXII, MMMMCDLXXXIII, MMMMCDLXXXIV, MMMMCDLXXXV, MMMMCDLXXXVI, MMMMCDLXXXVII, MMMMCDLXXXVIII, MMMMCDLXXXIX, MMMMCDXC, MMMMCDXCII, MMMMCDXCIII, MMMMCDXCIV, MMMMCDXCV, MMMMCDXCVI, MMMMCDXCVII, MMMMCDXCVIII, MMMMCDXCIX, MMMMD, MMMMDI, MMMMDII, MMMMDIII, MMMMDIV, MMMMDV, MMMMDVI, MMMMDVII, MMMMDVIII, MMMMDIX, MMMMDX