A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 693720 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 18 20 24 30 36 40 41 45 47 60 72 82 90 94 120 123 141 164 180 188 205 235 246 282 328 360 369 376 410 423 470 492 564 615 705 738 820 846 940 984 1,128 1,230 1,410 1,476 1,640 1,692 1,845 1,880 1,927 2,115 2,460 2,820 2,952 3,384 3,690 3,854 4,230 4,920 5,640 5,781 7,380 7,708 8,460 9,635 11,562 14,760 15,416 16,920 17,343 19,270 23,124 28,905 34,686 38,540 46,248 57,810 69,372 77,080 86,715 115,620 138,744 173,430 231,240 346,860 and 693,720, with no remainder.
Since 693,720 cannot be divided by just 1 and 693,720, it is not a prime number.