A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3960180 can be evenly divided by 1 2 3 4 5 6 7 9 10 12 14 15 18 20 21 28 30 35 36 42 45 49 60 63 70 84 90 98 105 126 140 147 180 196 210 245 252 294 315 420 441 449 490 588 630 735 882 898 980 1,260 1,347 1,470 1,764 1,796 2,205 2,245 2,694 2,940 3,143 4,041 4,410 4,490 5,388 6,286 6,735 8,082 8,820 8,980 9,429 12,572 13,470 15,715 16,164 18,858 20,205 22,001 26,940 28,287 31,430 37,716 40,410 44,002 47,145 56,574 62,860 66,003 80,820 88,004 94,290 110,005 113,148 132,006 141,435 188,580 198,009 220,010 264,012 282,870 330,015 396,018 440,020 565,740 660,030 792,036 990,045 1,320,060 1,980,090 and 3,960,180, with no remainder.
Since 3,960,180 cannot be divided by just 1 and 3,960,180, it is not a prime number.