A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8500608 can be evenly divided by 1 2 3 4 6 8 9 12 16 18 24 32 36 47 48 64 72 94 96 128 141 144 157 188 192 282 288 314 376 384 423 471 564 576 628 752 846 942 1,128 1,152 1,256 1,413 1,504 1,692 1,884 2,256 2,512 2,826 3,008 3,384 3,768 4,512 5,024 5,652 6,016 6,768 7,379 7,536 9,024 10,048 11,304 13,536 14,758 15,072 18,048 20,096 22,137 22,608 27,072 29,516 30,144 44,274 45,216 54,144 59,032 60,288 66,411 88,548 90,432 118,064 132,822 177,096 180,864 236,128 265,644 354,192 472,256 531,288 708,384 944,512 1,062,576 1,416,768 2,125,152 2,833,536 4,250,304 and 8,500,608, with no remainder.
Since 8,500,608 cannot be divided by just 1 and 8,500,608, it is not a prime number.