A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4886640 can be evenly divided by 1 2 3 4 5 6 8 9 10 11 12 15 16 18 20 22 24 30 33 36 40 44 45 48 55 60 66 72 80 88 90 99 110 120 132 144 165 176 180 198 220 240 264 330 360 396 440 495 528 617 660 720 792 880 990 1,234 1,320 1,584 1,851 1,980 2,468 2,640 3,085 3,702 3,960 4,936 5,553 6,170 6,787 7,404 7,920 9,255 9,872 11,106 12,340 13,574 14,808 18,510 20,361 22,212 24,680 27,148 27,765 29,616 33,935 37,020 40,722 44,424 49,360 54,296 55,530 61,083 67,870 74,040 81,444 88,848 101,805 108,592 111,060 122,166 135,740 148,080 162,888 203,610 222,120 244,332 271,480 305,415 325,776 407,220 444,240 488,664 542,960 610,830 814,440 977,328 1,221,660 1,628,880 2,443,320 and 4,886,640, with no remainder.
Since 4,886,640 cannot be divided by just 1 and 4,886,640, it is not a prime number.