A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2618000 can be evenly divided by 1 2 4 5 7 8 10 11 14 16 17 20 22 25 28 34 35 40 44 50 55 56 68 70 77 80 85 88 100 110 112 119 125 136 140 154 170 175 176 187 200 220 238 250 272 275 280 308 340 350 374 385 400 425 440 476 500 550 560 595 616 680 700 748 770 850 875 880 935 952 1,000 1,100 1,190 1,232 1,309 1,360 1,375 1,400 1,496 1,540 1,700 1,750 1,870 1,904 1,925 2,000 2,125 2,200 2,380 2,618 2,750 2,800 2,975 2,992 3,080 3,400 3,500 3,740 3,850 4,250 4,400 4,675 4,760 5,236 5,500 5,950 6,160 6,545 6,800 7,000 7,480 7,700 8,500 9,350 9,520 9,625 10,472 11,000 11,900 13,090 14,000 14,875 14,960 15,400 17,000 18,700 19,250 20,944 22,000 23,375 23,800 26,180 29,750 30,800 32,725 34,000 37,400 38,500 46,750 47,600 52,360 59,500 65,450 74,800 77,000 93,500 104,720 119,000 130,900 154,000 163,625 187,000 238,000 261,800 327,250 374,000 523,600 654,500 1,309,000 and 2,618,000, with no remainder.
Since 2,618,000 cannot be divided by just 1 and 2,618,000, it is not a prime number.