A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2163480 can be evenly divided by 1 2 3 4 5 6 8 10 11 12 15 20 22 24 30 33 40 44 55 60 66 88 110 120 121 132 149 165 220 242 264 298 330 363 440 447 484 596 605 660 726 745 894 968 1,192 1,210 1,320 1,452 1,490 1,639 1,788 1,815 2,235 2,420 2,904 2,980 3,278 3,576 3,630 4,470 4,840 4,917 5,960 6,556 7,260 8,195 8,940 9,834 13,112 14,520 16,390 17,880 18,029 19,668 24,585 32,780 36,058 39,336 49,170 54,087 65,560 72,116 90,145 98,340 108,174 144,232 180,290 196,680 216,348 270,435 360,580 432,696 540,870 721,160 1,081,740 and 2,163,480, with no remainder.
Since 2,163,480 cannot be divided by just 1 and 2,163,480, it is not a prime number.