A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 607320 can be evenly divided by 1 2 3 4 5 6 7 8 9 10 12 14 15 18 20 21 24 28 30 35 36 40 42 45 56 60 63 70 72 84 90 105 120 126 140 168 180 210 241 252 280 315 360 420 482 504 630 723 840 964 1,205 1,260 1,446 1,687 1,928 2,169 2,410 2,520 2,892 3,374 3,615 4,338 4,820 5,061 5,784 6,748 7,230 8,435 8,676 9,640 10,122 10,845 13,496 14,460 15,183 16,870 17,352 20,244 21,690 25,305 28,920 30,366 33,740 40,488 43,380 50,610 60,732 67,480 75,915 86,760 101,220 121,464 151,830 202,440 303,660 and 607,320, with no remainder.
Since 607,320 cannot be divided by just 1 and 607,320, it is not a prime number.