A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 6712920 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 18 20 24 29 30 36 40 45 58 60 72 87 90 116 120 145 174 180 232 261 290 348 360 435 522 580 643 696 870 1,044 1,160 1,286 1,305 1,740 1,929 2,088 2,572 2,610 3,215 3,480 3,858 5,144 5,220 5,787 6,430 7,716 9,645 10,440 11,574 12,860 15,432 18,647 19,290 23,148 25,720 28,935 37,294 38,580 46,296 55,941 57,870 74,588 77,160 93,235 111,882 115,740 149,176 167,823 186,470 223,764 231,480 279,705 335,646 372,940 447,528 559,410 671,292 745,880 839,115 1,118,820 1,342,584 1,678,230 2,237,640 3,356,460 and 6,712,920, with no remainder.
Since 6,712,920 cannot be divided by just 1 and 6,712,920, it is not a prime number.