A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3508120 can be evenly divided by 1 2 4 5 7 8 10 11 14 17 20 22 28 34 35 40 44 55 56 67 68 70 77 85 88 110 119 134 136 140 154 170 187 220 238 268 280 308 335 340 374 385 440 469 476 536 595 616 670 680 737 748 770 935 938 952 1,139 1,190 1,309 1,340 1,474 1,496 1,540 1,870 1,876 2,278 2,345 2,380 2,618 2,680 2,948 3,080 3,685 3,740 3,752 4,556 4,690 4,760 5,159 5,236 5,695 5,896 6,545 7,370 7,480 7,973 9,112 9,380 10,318 10,472 11,390 12,529 13,090 14,740 15,946 18,760 20,636 22,780 25,058 25,795 26,180 29,480 31,892 39,865 41,272 45,560 50,116 51,590 52,360 62,645 63,784 79,730 87,703 100,232 103,180 125,290 159,460 175,406 206,360 250,580 318,920 350,812 438,515 501,160 701,624 877,030 1,754,060 and 3,508,120, with no remainder.
Since 3,508,120 cannot be divided by just 1 and 3,508,120, it is not a prime number.