A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8601000 can be evenly divided by 1 2 3 4 5 6 8 10 12 15 20 24 25 30 40 47 50 60 61 75 94 100 120 122 125 141 150 183 188 200 235 244 250 282 300 305 366 375 376 470 488 500 564 600 610 705 732 750 915 940 1,000 1,128 1,175 1,220 1,410 1,464 1,500 1,525 1,830 1,880 2,350 2,440 2,820 2,867 3,000 3,050 3,525 3,660 4,575 4,700 5,640 5,734 5,875 6,100 7,050 7,320 7,625 8,601 9,150 9,400 11,468 11,750 12,200 14,100 14,335 15,250 17,202 17,625 18,300 22,875 22,936 23,500 28,200 28,670 30,500 34,404 35,250 36,600 43,005 45,750 47,000 57,340 61,000 68,808 70,500 71,675 86,010 91,500 114,680 141,000 143,350 172,020 183,000 215,025 286,700 344,040 358,375 430,050 573,400 716,750 860,100 1,075,125 1,433,500 1,720,200 2,150,250 2,867,000 4,300,500 and 8,601,000, with no remainder.
Since 8,601,000 cannot be divided by just 1 and 8,601,000, it is not a prime number.