A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4006240 can be evenly divided by 1 2 4 5 7 8 10 14 16 20 28 32 35 40 49 56 70 73 80 98 112 140 146 160 196 224 245 280 292 343 365 392 490 511 560 584 686 730 784 980 1,022 1,120 1,168 1,372 1,460 1,568 1,715 1,960 2,044 2,336 2,555 2,744 2,920 3,430 3,577 3,920 4,088 5,110 5,488 5,840 6,860 7,154 7,840 8,176 10,220 10,976 11,680 13,720 14,308 16,352 17,885 20,440 25,039 27,440 28,616 35,770 40,880 50,078 54,880 57,232 71,540 81,760 100,156 114,464 125,195 143,080 200,312 250,390 286,160 400,624 500,780 572,320 801,248 1,001,560 2,003,120 and 4,006,240, with no remainder.
Since 4,006,240 cannot be divided by just 1 and 4,006,240, it is not a prime number.