A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8733420 can be evenly divided by 1 2 3 4 5 6 9 10 12 15 18 20 27 30 36 45 54 60 81 90 108 135 162 180 243 270 324 405 486 540 599 729 810 972 1,198 1,215 1,458 1,620 1,797 2,396 2,430 2,916 2,995 3,594 3,645 4,860 5,391 5,990 7,188 7,290 8,985 10,782 11,980 14,580 16,173 17,970 21,564 26,955 32,346 35,940 48,519 53,910 64,692 80,865 97,038 107,820 145,557 161,730 194,076 242,595 291,114 323,460 436,671 485,190 582,228 727,785 873,342 970,380 1,455,570 1,746,684 2,183,355 2,911,140 4,366,710 and 8,733,420, with no remainder.
Since 8,733,420 cannot be divided by just 1 and 8,733,420, it is not a prime number.