Il numero romano MDCCXCI nel sistema decimale vale: 1791.
MDCCXCI in latino si scrive mille septingenti nonaginta unus,
mentre in italiano millesettecentonovantuno.
MDCCLXXII, MDCCLXXIII, MDCCLXXIV, MDCCLXXV, MDCCLXXVI, MDCCLXXVII, MDCCLXXVIII, MDCCLXXIX, MDCCLXXX, MDCCLXXXI, MDCCLXXXII, MDCCLXXXIII, MDCCLXXXIV, MDCCLXXXV, MDCCLXXXVI, MDCCLXXXVII, MDCCLXXXVIII, MDCCLXXXIX, MDCCXC, MDCCXCII, MDCCXCIII, MDCCXCIV, MDCCXCV, MDCCXCVI, MDCCXCVII, MDCCXCVIII, MDCCXCIX, MDCCC, MDCCCI, MDCCCII, MDCCCIII, MDCCCIV, MDCCCV, MDCCCVI, MDCCCVII, MDCCCVIII, MDCCCIX, MDCCCX