Il numero romano MMDCCCXCI nel sistema decimale vale: 2891.
MMDCCCXCI in latino si scrive duo milia octingenti nonaginta unus,
mentre in italiano duemilaottocentonovantuno.
MMDCCCLXXII, MMDCCCLXXIII, MMDCCCLXXIV, MMDCCCLXXV, MMDCCCLXXVI, MMDCCCLXXVII, MMDCCCLXXVIII, MMDCCCLXXIX, MMDCCCLXXX, MMDCCCLXXXI, MMDCCCLXXXII, MMDCCCLXXXIII, MMDCCCLXXXIV, MMDCCCLXXXV, MMDCCCLXXXVI, MMDCCCLXXXVII, MMDCCCLXXXVIII, MMDCCCLXXXIX, MMDCCCXC, MMDCCCXCII, MMDCCCXCIII, MMDCCCXCIV, MMDCCCXCV, MMDCCCXCVI, MMDCCCXCVII, MMDCCCXCVIII, MMDCCCXCIX, MMCM, MMCMI, MMCMII, MMCMIII, MMCMIV, MMCMV, MMCMVI, MMCMVII, MMCMVIII, MMCMIX, MMCMX