A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4384640 can be evenly divided by 1 2 4 5 8 10 13 16 17 20 26 31 32 34 40 52 62 64 65 68 80 85 104 124 128 130 136 155 160 170 208 221 248 260 272 310 320 340 403 416 442 496 520 527 544 620 640 680 806 832 884 992 1,040 1,054 1,088 1,105 1,240 1,360 1,612 1,664 1,768 1,984 2,015 2,080 2,108 2,176 2,210 2,480 2,635 2,720 3,224 3,536 3,968 4,030 4,160 4,216 4,420 4,960 5,270 5,440 6,448 6,851 7,072 8,060 8,320 8,432 8,840 9,920 10,540 10,880 12,896 13,702 14,144 16,120 16,864 17,680 19,840 21,080 25,792 27,404 28,288 32,240 33,728 34,255 35,360 42,160 51,584 54,808 64,480 67,456 68,510 70,720 84,320 109,616 128,960 137,020 141,440 168,640 219,232 257,920 274,040 337,280 438,464 548,080 876,928 1,096,160 2,192,320 and 4,384,640, with no remainder.
Since 4,384,640 cannot be divided by just 1 and 4,384,640, it is not a prime number.