The factors of the number 6,561,555 are: 1, 3, 5, 7, 11, 13, 15, 19, 21, 23, 33, 35, 39, 55, 57, 65, 69, 77, 91, 95, 105, 115, 133, 143, 161, 165, 195, 209, 231, 247, 253, 273, 285, 299, 345, 385, 399, 429, 437, 455, 483, 627, 665, 715, 741, 759, 805, 897, 1001, 1045, 1155, 1235, 1265, 1311, 1365, 1463, 1495, 1729, 1771, 1995, 2093, 2145, 2185, 2415, 2717, 3003, 3059, 3135, 3289, 3705, 3795, 4389, 4485, 4807, 5005, 5187, 5313, 5681, 6279, 6555, 7315, 8151, 8645, 8855, 9177, 9867, 10465, 13585, 14421, 15015, 15295, 16445, 17043, 19019, 21945, 23023, 24035, 25935, 26565, 28405, 31395, 33649, 39767, 40755, 45885, 49335, 57057, 62491, 69069, 72105, 85215, 95095, 100947, 115115, 119301, 168245, 187473, 198835, 285285, 312455, 345345, 437437, 504735, 596505, 937365, 1312311, 2187185, 6561555.
If you add them up, you will get the total of 15,482,880.