A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3228120 can be evenly divided by 1 2 3 4 5 6 7 8 9 10 12 14 15 18 20 21 24 27 28 30 35 36 40 42 45 49 54 56 60 61 63 70 72 84 90 98 105 108 120 122 126 135 140 147 168 180 183 189 196 210 216 244 245 252 270 280 294 305 315 360 366 378 392 420 427 441 488 490 504 540 549 588 610 630 732 735 756 840 854 882 915 945 980 1,080 1,098 1,176 1,220 1,260 1,281 1,323 1,464 1,470 1,512 1,647 1,708 1,764 1,830 1,890 1,960 2,135 2,196 2,205 2,440 2,520 2,562 2,646 2,745 2,940 2,989 3,294 3,416 3,528 3,660 3,780 3,843 4,270 4,392 4,410 5,124 5,292 5,490 5,880 5,978 6,405 6,588 6,615 7,320 7,560 7,686 8,235 8,540 8,820 8,967 10,248 10,584 10,980 11,529 11,956 12,810 13,176 13,230 14,945 15,372 16,470 17,080 17,640 17,934 19,215 21,960 23,058 23,912 25,620 26,460 26,901 29,890 30,744 32,940 35,868 38,430 44,835 46,116 51,240 52,920 53,802 57,645 59,780 65,880 71,736 76,860 80,703 89,670 92,232 107,604 115,290 119,560 134,505 153,720 161,406 179,340 215,208 230,580 269,010 322,812 358,680 403,515 461,160 538,020 645,624 807,030 1,076,040 1,614,060 and 3,228,120, with no remainder.
Since 3,228,120 cannot be divided by just 1 and 3,228,120, it is not a prime number.