A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3403620 can be evenly divided by 1 2 3 4 5 6 9 10 11 12 15 18 20 22 27 30 33 36 44 45 54 55 60 66 81 90 99 108 110 132 135 162 165 180 191 198 220 270 297 324 330 382 396 405 495 540 573 594 660 764 810 891 955 990 1,146 1,188 1,485 1,620 1,719 1,782 1,910 1,980 2,101 2,292 2,865 2,970 3,438 3,564 3,820 4,202 4,455 5,157 5,730 5,940 6,303 6,876 8,404 8,595 8,910 10,314 10,505 11,460 12,606 15,471 17,190 17,820 18,909 20,628 21,010 25,212 25,785 30,942 31,515 34,380 37,818 42,020 51,570 56,727 61,884 63,030 75,636 77,355 94,545 103,140 113,454 126,060 154,710 170,181 189,090 226,908 283,635 309,420 340,362 378,180 567,270 680,724 850,905 1,134,540 1,701,810 and 3,403,620, with no remainder.
Since 3,403,620 cannot be divided by just 1 and 3,403,620, it is not a prime number.