The number 3,551,100 can be evenly divided by 1 2 3 4 5 6 7 10 12 14 15 19 20 21 25 28 30 35 38 42 50 57 60 70 75 76 84 89 95 100 105 114 133 140 150 175 178 190 210 228 266 267 285 300 350 356 380 399 420 445 475 525 532 534 570 623 665 700 798 890 950 1,050 1,068 1,140 1,246 1,330 1,335 1,425 1,596 1,691 1,780 1,869 1,900 1,995 2,100 2,225 2,492 2,660 2,670 2,850 3,115 3,325 3,382 3,738 3,990 4,450 5,073 5,340 5,700 6,230 6,650 6,675 6,764 7,476 7,980 8,455 8,900 9,345 9,975 10,146 11,837 12,460 13,300 13,350 15,575 16,910 18,690 19,950 20,292 23,674 25,365 26,700 31,150 33,820 35,511 37,380 39,900 42,275 46,725 47,348 50,730 59,185 62,300 71,022 84,550 93,450 101,460 118,370 126,825 142,044 169,100 177,555 186,900 236,740 253,650 295,925 355,110 507,300 591,850 710,220 887,775 1,183,700 1,775,550 and 3,551,100, with no remainder.
Since 3,551,100 cannot be divided by just 1 and 3,551,100, it is a composite number.