The factors of the number 1,551,312 are: 1, 2, 3, 4, 6, 7, 8, 9, 12, 14, 16, 18, 19, 21, 24, 27, 28, 36, 38, 42, 48, 54, 56, 57, 63, 72, 76, 81, 84, 108, 112, 114, 126, 133, 144, 152, 162, 168, 171, 189, 216, 228, 243, 252, 266, 304, 324, 336, 342, 378, 399, 432, 456, 486, 504, 513, 532, 567, 648, 684, 729, 756, 798, 912, 972, 1008, 1026, 1064, 1134, 1197, 1296, 1368, 1458, 1512, 1539, 1596, 1701, 1944, 2052, 2128, 2268, 2394, 2736, 2916, 3024, 3078, 3192, 3402, 3591, 3888, 4104, 4536, 4617, 4788, 5103, 5832, 6156, 6384, 6804, 7182, 8208, 9072, 9234, 9576, 10206, 10773, 11664, 12312, 13608, 13851, 14364, 18468, 19152, 20412, 21546, 24624, 27216, 27702, 28728, 32319, 36936, 40824, 43092, 55404, 57456, 64638, 73872, 81648, 86184, 96957, 110808, 129276, 172368, 193914, 221616, 258552, 387828, 517104, 775656, 1551312.
If you add them up, you will get the total of 5,421,280.