A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8040384 can be evenly divided by 1 2 3 4 6 8 9 11 12 16 18 22 24 27 32 33 36 44 47 48 54 64 66 72 81 88 94 96 99 108 132 141 144 162 176 188 192 198 216 243 264 282 288 297 324 352 376 396 423 432 486 517 528 564 576 594 648 704 752 792 846 864 891 972 1,034 1,056 1,128 1,188 1,269 1,296 1,504 1,551 1,584 1,692 1,728 1,782 1,944 2,068 2,112 2,256 2,376 2,538 2,592 2,673 3,008 3,102 3,168 3,384 3,564 3,807 3,888 4,136 4,512 4,653 4,752 5,076 5,184 5,346 6,204 6,336 6,768 7,128 7,614 7,776 8,272 9,024 9,306 9,504 10,152 10,692 11,421 12,408 13,536 13,959 14,256 15,228 15,552 16,544 18,612 19,008 20,304 21,384 22,842 24,816 27,072 27,918 28,512 30,456 33,088 37,224 40,608 41,877 42,768 45,684 49,632 55,836 57,024 60,912 74,448 81,216 83,754 85,536 91,368 99,264 111,672 121,824 125,631 148,896 167,508 171,072 182,736 223,344 243,648 251,262 297,792 335,016 365,472 446,688 502,524 670,032 730,944 893,376 1,005,048 1,340,064 2,010,096 2,680,128 4,020,192 and 8,040,384, with no remainder.
Since 8,040,384 cannot be divided by just 1 and 8,040,384, it is not a prime number.