A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2452128 can be evenly divided by 1 2 3 4 6 7 8 12 14 16 21 24 28 32 41 42 48 56 82 84 89 96 112 123 164 168 178 224 246 267 287 328 336 356 492 534 574 623 656 672 712 861 984 1,068 1,148 1,246 1,312 1,424 1,722 1,869 1,968 2,136 2,296 2,492 2,848 3,444 3,649 3,738 3,936 4,272 4,592 4,984 6,888 7,298 7,476 8,544 9,184 9,968 10,947 13,776 14,596 14,952 19,936 21,894 25,543 27,552 29,192 29,904 43,788 51,086 58,384 59,808 76,629 87,576 102,172 116,768 153,258 175,152 204,344 306,516 350,304 408,688 613,032 817,376 1,226,064 and 2,452,128, with no remainder.
Since 2,452,128 cannot be divided by just 1 and 2,452,128, it is not a prime number.