Il numero romano MMMDLXXXI nel sistema decimale vale: 3581.
MMMDLXXXI in latino si scrive tria milia quingenti octoginta unus,
mentre in italiano tremilacinquecentottantuno.
MMMDLXII, MMMDLXIII, MMMDLXIV, MMMDLXV, MMMDLXVI, MMMDLXVII, MMMDLXVIII, MMMDLXIX, MMMDLXX, MMMDLXXI, MMMDLXXII, MMMDLXXIII, MMMDLXXIV, MMMDLXXV, MMMDLXXVI, MMMDLXXVII, MMMDLXXVIII, MMMDLXXIX, MMMDLXXX, MMMDLXXXII, MMMDLXXXIII, MMMDLXXXIV, MMMDLXXXV, MMMDLXXXVI, MMMDLXXXVII, MMMDLXXXVIII, MMMDLXXXIX, MMMDXC, MMMDXCI, MMMDXCII, MMMDXCIII, MMMDXCIV, MMMDXCV, MMMDXCVI, MMMDXCVII, MMMDXCVIII, MMMDXCIX, MMMDC