The number 1,098,240 can be evenly divided by 1 2 3 4 5 6 8 10 11 12 13 15 16 20 22 24 26 30 32 33 39 40 44 48 52 55 60 64 65 66 78 80 88 96 104 110 120 128 130 132 143 156 160 165 176 192 195 208 220 240 256 260 264 286 312 320 330 352 384 390 416 429 440 480 512 520 528 572 624 640 660 704 715 768 780 832 858 880 960 1,040 1,056 1,144 1,248 1,280 1,320 1,408 1,430 1,536 1,560 1,664 1,716 1,760 1,920 2,080 2,112 2,145 2,288 2,496 2,560 2,640 2,816 2,860 3,120 3,328 3,432 3,520 3,840 4,160 4,224 4,290 4,576 4,992 5,280 5,632 5,720 6,240 6,656 6,864 7,040 7,680 8,320 8,448 8,580 9,152 9,984 10,560 11,440 12,480 13,728 14,080 16,640 16,896 17,160 18,304 19,968 21,120 22,880 24,960 27,456 28,160 33,280 34,320 36,608 42,240 45,760 49,920 54,912 68,640 73,216 84,480 91,520 99,840 109,824 137,280 183,040 219,648 274,560 366,080 549,120 and 1,098,240, with no remainder.
Since 1,098,240 cannot be divided by just 1 and 1,098,240, it is a composite number.