A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3501792 can be evenly divided by 1 2 3 4 6 7 8 9 12 14 16 18 21 24 27 28 32 36 42 48 54 56 63 72 81 84 96 108 112 126 144 162 168 189 193 216 224 252 288 324 336 378 386 432 504 567 579 648 672 756 772 864 1,008 1,134 1,158 1,296 1,351 1,512 1,544 1,737 2,016 2,268 2,316 2,592 2,702 3,024 3,088 3,474 4,053 4,536 4,632 5,211 5,404 6,048 6,176 6,948 8,106 9,072 9,264 10,422 10,808 12,159 13,896 15,633 16,212 18,144 18,528 20,844 21,616 24,318 27,792 31,266 32,424 36,477 41,688 43,232 48,636 55,584 62,532 64,848 72,954 83,376 97,272 109,431 125,064 129,696 145,908 166,752 194,544 218,862 250,128 291,816 389,088 437,724 500,256 583,632 875,448 1,167,264 1,750,896 and 3,501,792, with no remainder.
Since 3,501,792 cannot be divided by just 1 and 3,501,792, it is not a prime number.