A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4002720 can be evenly divided by 1 2 3 4 5 6 8 10 12 15 16 20 24 30 31 32 40 48 60 62 80 93 96 120 124 155 160 186 240 248 269 310 372 465 480 496 538 620 744 807 930 992 1,076 1,240 1,345 1,488 1,614 1,860 2,152 2,480 2,690 2,976 3,228 3,720 4,035 4,304 4,960 5,380 6,456 7,440 8,070 8,339 8,608 10,760 12,912 14,880 16,140 16,678 21,520 25,017 25,824 32,280 33,356 41,695 43,040 50,034 64,560 66,712 83,390 100,068 125,085 129,120 133,424 166,780 200,136 250,170 266,848 333,560 400,272 500,340 667,120 800,544 1,000,680 1,334,240 2,001,360 and 4,002,720, with no remainder.
Since 4,002,720 cannot be divided by just 1 and 4,002,720, it is not a prime number.