The number 1,643,400 can be evenly divided by 1 2 3 4 5 6 8 9 10 11 12 15 18 20 22 24 25 30 33 36 40 44 45 50 55 60 66 72 75 83 88 90 99 100 110 120 132 150 165 166 180 198 200 220 225 249 264 275 300 330 332 360 396 415 440 450 495 498 550 600 660 664 747 792 825 830 900 913 990 996 1,100 1,245 1,320 1,494 1,650 1,660 1,800 1,826 1,980 1,992 2,075 2,200 2,475 2,490 2,739 2,988 3,300 3,320 3,652 3,735 3,960 4,150 4,565 4,950 4,980 5,478 5,976 6,225 6,600 7,304 7,470 8,217 8,300 9,130 9,900 9,960 10,956 12,450 13,695 14,940 16,434 16,600 18,260 18,675 19,800 21,912 22,825 24,900 27,390 29,880 32,868 36,520 37,350 41,085 45,650 49,800 54,780 65,736 68,475 74,700 82,170 91,300 109,560 136,950 149,400 164,340 182,600 205,425 273,900 328,680 410,850 547,800 821,700 and 1,643,400, with no remainder.
Since 1,643,400 cannot be divided by just 1 and 1,643,400, it is a composite number.