The number 2,161,440 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 16 18 19 20 24 30 32 36 38 40 45 48 57 60 72 76 79 80 90 95 96 114 120 144 152 158 160 171 180 190 228 237 240 285 288 304 316 342 360 380 395 456 474 480 570 608 632 684 711 720 760 790 855 912 948 1,140 1,185 1,264 1,368 1,422 1,440 1,501 1,520 1,580 1,710 1,824 1,896 2,280 2,370 2,528 2,736 2,844 3,002 3,040 3,160 3,420 3,555 3,792 4,503 4,560 4,740 5,472 5,688 6,004 6,320 6,840 7,110 7,505 7,584 9,006 9,120 9,480 11,376 12,008 12,640 13,509 13,680 14,220 15,010 18,012 18,960 22,515 22,752 24,016 27,018 27,360 28,440 30,020 36,024 37,920 45,030 48,032 54,036 56,880 60,040 67,545 72,048 90,060 108,072 113,760 120,080 135,090 144,096 180,120 216,144 240,160 270,180 360,240 432,288 540,360 720,480 1,080,720 and 2,161,440, with no remainder.
Since 2,161,440 cannot be divided by just 1 and 2,161,440, it is a composite number.