The number 2,556,720 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 16 18 20 24 30 36 40 45 48 53 60 67 72 80 90 106 120 134 144 159 180 201 212 240 265 268 318 335 360 402 424 477 530 536 603 636 670 720 795 804 848 954 1,005 1,060 1,072 1,206 1,272 1,340 1,590 1,608 1,908 2,010 2,120 2,385 2,412 2,544 2,680 3,015 3,180 3,216 3,551 3,816 4,020 4,240 4,770 4,824 5,360 6,030 6,360 7,102 7,632 8,040 9,540 9,648 10,653 12,060 12,720 14,204 16,080 17,755 19,080 21,306 24,120 28,408 31,959 35,510 38,160 42,612 48,240 53,265 56,816 63,918 71,020 85,224 106,530 127,836 142,040 159,795 170,448 213,060 255,672 284,080 319,590 426,120 511,344 639,180 852,240 1,278,360 and 2,556,720, with no remainder.
Since 2,556,720 cannot be divided by just 1 and 2,556,720, it is a composite number.