A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3985344 can be evenly divided by 1 2 3 4 6 8 9 11 12 16 17 18 22 24 32 33 34 36 37 44 48 51 64 66 68 72 74 88 96 99 102 111 132 136 144 148 153 176 187 192 198 204 222 264 272 288 296 306 333 352 374 396 407 408 444 528 544 561 576 592 612 629 666 704 748 792 814 816 888 1,056 1,088 1,122 1,184 1,221 1,224 1,258 1,332 1,496 1,584 1,628 1,632 1,683 1,776 1,887 2,112 2,244 2,368 2,442 2,448 2,516 2,664 2,992 3,168 3,256 3,264 3,366 3,552 3,663 3,774 4,488 4,884 4,896 5,032 5,328 5,661 5,984 6,336 6,512 6,732 6,919 7,104 7,326 7,548 8,976 9,768 9,792 10,064 10,656 11,322 11,968 13,024 13,464 13,838 14,652 15,096 17,952 19,536 20,128 20,757 21,312 22,644 26,048 26,928 27,676 29,304 30,192 35,904 39,072 40,256 41,514 45,288 53,856 55,352 58,608 60,384 62,271 78,144 83,028 90,576 107,712 110,704 117,216 120,768 124,542 166,056 181,152 221,408 234,432 249,084 332,112 362,304 442,816 498,168 664,224 996,336 1,328,448 1,992,672 and 3,985,344, with no remainder.
Since 3,985,344 cannot be divided by just 1 and 3,985,344, it is not a prime number.