A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 624360 can be evenly divided by 1 2 3 4 5 6 8 10 11 12 15 20 22 24 30 33 40 43 44 55 60 66 86 88 110 120 121 129 132 165 172 215 220 242 258 264 330 344 363 430 440 473 484 516 605 645 660 726 860 946 968 1,032 1,210 1,290 1,320 1,419 1,452 1,720 1,815 1,892 2,365 2,420 2,580 2,838 2,904 3,630 3,784 4,730 4,840 5,160 5,203 5,676 7,095 7,260 9,460 10,406 11,352 14,190 14,520 15,609 18,920 20,812 26,015 28,380 31,218 41,624 52,030 56,760 62,436 78,045 104,060 124,872 156,090 208,120 312,180 and 624,360, with no remainder.
Since 624,360 cannot be divided by just 1 and 624,360, it is not a prime number.