A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1625184 can be evenly divided by 1 2 3 4 6 8 9 11 12 16 18 19 22 24 27 32 33 36 38 44 48 54 57 66 72 76 81 88 96 99 108 114 132 144 152 162 171 176 198 209 216 228 243 264 288 297 304 324 342 352 396 418 432 456 486 513 528 594 608 627 648 684 792 836 864 891 912 972 1,026 1,056 1,188 1,254 1,296 1,368 1,539 1,584 1,672 1,782 1,824 1,881 1,944 2,052 2,376 2,508 2,592 2,673 2,736 3,078 3,168 3,344 3,564 3,762 3,888 4,104 4,617 4,752 5,016 5,346 5,472 5,643 6,156 6,688 7,128 7,524 7,776 8,208 9,234 9,504 10,032 10,692 11,286 12,312 14,256 15,048 16,416 16,929 18,468 20,064 21,384 22,572 24,624 28,512 30,096 33,858 36,936 42,768 45,144 49,248 50,787 60,192 67,716 73,872 85,536 90,288 101,574 135,432 147,744 180,576 203,148 270,864 406,296 541,728 812,592 and 1,625,184, with no remainder.
Since 1,625,184 cannot be divided by just 1 and 1,625,184, it is not a prime number.