The number 6,436,320 can be evenly divided by 1 2 3 4 5 6 8 10 11 12 15 16 20 22 23 24 30 32 33 40 44 46 48 53 55 60 66 69 80 88 92 96 106 110 115 120 132 138 159 160 165 176 184 212 220 230 240 253 264 265 276 318 330 345 352 368 424 440 460 480 506 528 530 552 583 636 660 690 736 759 795 848 880 920 1,012 1,056 1,060 1,104 1,166 1,219 1,265 1,272 1,320 1,380 1,518 1,590 1,696 1,749 1,760 1,840 2,024 2,120 2,208 2,332 2,438 2,530 2,544 2,640 2,760 2,915 3,036 3,180 3,498 3,657 3,680 3,795 4,048 4,240 4,664 4,876 5,060 5,088 5,280 5,520 5,830 6,072 6,095 6,360 6,996 7,314 7,590 8,096 8,480 8,745 9,328 9,752 10,120 11,040 11,660 12,144 12,190 12,720 13,409 13,992 14,628 15,180 17,490 18,285 18,656 19,504 20,240 23,320 24,288 24,380 25,440 26,818 27,984 29,256 30,360 34,980 36,570 39,008 40,227 40,480 46,640 48,760 53,636 55,968 58,512 60,720 67,045 69,960 73,140 80,454 93,280 97,520 107,272 117,024 121,440 134,090 139,920 146,280 160,908 195,040 201,135 214,544 268,180 279,840 292,560 321,816 402,270 429,088 536,360 585,120 643,632 804,540 1,072,720 1,287,264 1,609,080 2,145,440 3,218,160 and 6,436,320, with no remainder.
Since 6,436,320 cannot be divided by just 1 and 6,436,320, it is a composite number.