A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2179485 can be evenly divided by 1 3 5 7 9 11 15 17 21 33 35 37 45 51 55 63 77 85 99 105 111 119 153 165 185 187 231 255 259 315 333 357 385 407 495 555 561 595 629 693 765 777 935 1,071 1,155 1,221 1,295 1,309 1,665 1,683 1,785 1,887 2,035 2,331 2,805 2,849 3,145 3,465 3,663 3,885 3,927 4,403 5,355 5,661 6,105 6,545 6,919 8,415 8,547 9,435 11,655 11,781 13,209 14,245 18,315 19,635 20,757 22,015 25,641 28,305 34,595 39,627 42,735 48,433 58,905 62,271 66,045 103,785 128,205 145,299 198,135 242,165 311,355 435,897 726,495 and 2,179,485, with no remainder.
Since 2,179,485 cannot be divided by just 1 and 2,179,485, it is not a prime number.