A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8009640 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 18 19 20 24 30 36 38 40 45 57 60 72 76 90 95 114 120 152 171 180 190 228 285 342 360 380 456 570 684 760 855 1,140 1,171 1,368 1,710 2,280 2,342 3,420 3,513 4,684 5,855 6,840 7,026 9,368 10,539 11,710 14,052 17,565 21,078 22,249 23,420 28,104 35,130 42,156 44,498 46,840 52,695 66,747 70,260 84,312 88,996 105,390 111,245 133,494 140,520 177,992 200,241 210,780 222,490 266,988 333,735 400,482 421,560 444,980 533,976 667,470 800,964 889,960 1,001,205 1,334,940 1,601,928 2,002,410 2,669,880 4,004,820 and 8,009,640, with no remainder.
Since 8,009,640 cannot be divided by just 1 and 8,009,640, it is not a prime number.