A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2191280 can be evenly divided by 1 2 4 5 7 8 10 13 14 16 20 26 28 35 40 43 49 52 56 65 70 80 86 91 98 104 112 130 140 172 182 196 208 215 245 260 280 301 344 364 392 430 455 490 520 559 560 602 637 688 728 784 860 910 980 1,040 1,118 1,204 1,274 1,456 1,505 1,720 1,820 1,960 2,107 2,236 2,408 2,548 2,795 3,010 3,185 3,440 3,640 3,913 3,920 4,214 4,472 4,816 5,096 5,590 6,020 6,370 7,280 7,826 8,428 8,944 10,192 10,535 11,180 12,040 12,740 15,652 16,856 19,565 21,070 22,360 24,080 25,480 27,391 31,304 33,712 39,130 42,140 44,720 50,960 54,782 62,608 78,260 84,280 109,564 136,955 156,520 168,560 219,128 273,910 313,040 438,256 547,820 1,095,640 and 2,191,280, with no remainder.
Since 2,191,280 cannot be divided by just 1 and 2,191,280, it is not a prime number.