A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3520260 can be evenly divided by 1 2 3 4 5 6 9 10 12 15 18 20 27 30 36 41 45 53 54 60 81 82 90 106 108 123 135 159 162 164 180 205 212 246 265 270 318 324 369 405 410 477 492 530 540 615 636 738 795 810 820 954 1,060 1,107 1,230 1,431 1,476 1,590 1,620 1,845 1,908 2,173 2,214 2,385 2,460 2,862 3,180 3,321 3,690 4,293 4,346 4,428 4,770 5,535 5,724 6,519 6,642 7,155 7,380 8,586 8,692 9,540 10,865 11,070 13,038 13,284 14,310 16,605 17,172 19,557 21,465 21,730 22,140 26,076 28,620 32,595 33,210 39,114 42,930 43,460 58,671 65,190 66,420 78,228 85,860 97,785 117,342 130,380 176,013 195,570 234,684 293,355 352,026 391,140 586,710 704,052 880,065 1,173,420 1,760,130 and 3,520,260, with no remainder.
Since 3,520,260 cannot be divided by just 1 and 3,520,260, it is not a prime number.