A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 7205256 can be evenly divided by 1 2 3 4 6 8 9 12 18 19 23 24 36 38 46 57 69 72 76 92 114 138 152 171 184 207 228 229 276 342 414 437 456 458 552 684 687 828 874 916 1,311 1,368 1,374 1,656 1,748 1,832 2,061 2,622 2,748 3,496 3,933 4,122 4,351 5,244 5,267 5,496 7,866 8,244 8,702 10,488 10,534 13,053 15,732 15,801 16,488 17,404 21,068 26,106 31,464 31,602 34,808 39,159 42,136 47,403 52,212 63,204 78,318 94,806 100,073 104,424 126,408 156,636 189,612 200,146 300,219 313,272 379,224 400,292 600,438 800,584 900,657 1,200,876 1,801,314 2,401,752 3,602,628 and 7,205,256, with no remainder.
Since 7,205,256 cannot be divided by just 1 and 7,205,256, it is not a prime number.