A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 5960556 can be evenly divided by 1 2 3 4 6 7 9 12 14 18 21 28 31 36 42 49 62 63 84 93 98 109 124 126 147 186 196 217 218 252 279 294 327 372 434 436 441 558 588 651 654 763 868 882 981 1,116 1,302 1,308 1,519 1,526 1,764 1,953 1,962 2,289 2,604 3,038 3,052 3,379 3,906 3,924 4,557 4,578 5,341 6,076 6,758 6,867 7,812 9,114 9,156 10,137 10,682 13,516 13,671 13,734 16,023 18,228 20,274 21,364 23,653 27,342 27,468 30,411 32,046 40,548 47,306 48,069 54,684 60,822 64,092 70,959 94,612 96,138 121,644 141,918 165,571 192,276 212,877 283,836 331,142 425,754 496,713 662,284 851,508 993,426 1,490,139 1,986,852 2,980,278 and 5,960,556, with no remainder.
Since 5,960,556 cannot be divided by just 1 and 5,960,556, it is not a prime number.