I divisori di 19911991 sono 16, elencati qui di seguito: 1; 11; 73; 137; 181; 803; 1507; 1991; 10001; 13213; 24797; 110011; 145343; 272767; 1810181; 19911991
19911972, 19911973, 19911974, 19911975, 19911976, 19911977, 19911978, 19911979, 19911980, 19911981, 19911982, 19911983, 19911984, 19911985, 19911986, 19911987, 19911988, 19911989, 19911990, 19911992, 19911993, 19911994, 19911995, 19911996, 19911997, 19911998, 19911999, 19912000, 19912001, 19912002, 19912003, 19912004, 19912005, 19912006, 19912007, 19912008, 19912009, 19912010