A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1693536 can be evenly divided by 1 2 3 4 6 8 12 13 16 23 24 26 32 39 46 48 52 59 69 78 92 96 104 118 138 156 177 184 208 236 276 299 312 354 368 416 472 552 598 624 708 736 767 897 944 1,104 1,196 1,248 1,357 1,416 1,534 1,794 1,888 2,208 2,301 2,392 2,714 2,832 3,068 3,588 4,071 4,602 4,784 5,428 5,664 6,136 7,176 8,142 9,204 9,568 10,856 12,272 14,352 16,284 17,641 18,408 21,712 24,544 28,704 32,568 35,282 36,816 43,424 52,923 65,136 70,564 73,632 105,846 130,272 141,128 211,692 282,256 423,384 564,512 846,768 and 1,693,536, with no remainder.
Since 1,693,536 cannot be divided by just 1 and 1,693,536, it is not a prime number.