A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 365904 can be evenly divided by 1 2 3 4 6 7 8 9 11 12 14 16 18 21 22 24 27 28 33 36 42 44 48 54 56 63 66 72 77 84 88 99 108 112 121 126 132 144 154 168 176 189 198 216 231 242 252 264 297 308 336 363 378 396 432 462 484 504 528 594 616 693 726 756 792 847 924 968 1,008 1,089 1,188 1,232 1,386 1,452 1,512 1,584 1,694 1,848 1,936 2,079 2,178 2,376 2,541 2,772 2,904 3,024 3,267 3,388 3,696 4,158 4,356 4,752 5,082 5,544 5,808 6,534 6,776 7,623 8,316 8,712 10,164 11,088 13,068 13,552 15,246 16,632 17,424 20,328 22,869 26,136 30,492 33,264 40,656 45,738 52,272 60,984 91,476 121,968 182,952 and 365,904, with no remainder.
Since 365,904 cannot be divided by just 1 and 365,904, it is not a prime number.