A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1459584 can be evenly divided by 1 2 3 4 6 7 8 9 12 14 16 18 21 24 28 32 36 42 48 56 63 64 72 84 96 112 126 128 144 168 181 192 224 252 288 336 362 384 448 504 543 576 672 724 896 1,008 1,086 1,152 1,267 1,344 1,448 1,629 2,016 2,172 2,534 2,688 2,896 3,258 3,801 4,032 4,344 5,068 5,792 6,516 7,602 8,064 8,688 10,136 11,403 11,584 13,032 15,204 17,376 20,272 22,806 23,168 26,064 30,408 34,752 40,544 45,612 52,128 60,816 69,504 81,088 91,224 104,256 121,632 162,176 182,448 208,512 243,264 364,896 486,528 729,792 and 1,459,584, with no remainder.
Since 1,459,584 cannot be divided by just 1 and 1,459,584, it is not a prime number.