A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 5276502 can be evenly divided by 1 2 3 6 7 9 11 14 18 21 22 27 33 42 47 54 63 66 77 81 94 99 126 141 154 162 189 198 231 243 282 297 329 378 423 462 486 517 567 594 658 693 729 846 891 987 1,034 1,134 1,269 1,386 1,458 1,551 1,701 1,782 1,974 2,079 2,538 2,673 2,961 3,102 3,402 3,619 3,807 4,158 4,653 5,103 5,346 5,922 6,237 7,238 7,614 8,019 8,883 9,306 10,206 10,857 11,421 12,474 13,959 16,038 17,766 18,711 21,714 22,842 26,649 27,918 32,571 34,263 37,422 41,877 53,298 56,133 65,142 68,526 79,947 83,754 97,713 112,266 125,631 159,894 195,426 239,841 251,262 293,139 376,893 479,682 586,278 753,786 879,417 1,758,834 2,638,251 and 5,276,502, with no remainder.
Since 5,276,502 cannot be divided by just 1 and 5,276,502, it is not a prime number.