A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 5577768 can be evenly divided by 1 2 3 4 6 7 8 9 12 14 17 18 21 24 27 28 31 34 36 42 49 51 54 56 62 63 68 72 84 93 98 102 108 119 124 126 136 147 153 168 186 189 196 204 216 217 238 248 252 279 294 306 357 372 378 392 408 434 441 459 476 504 527 558 588 612 651 714 744 756 833 837 868 882 918 952 1,054 1,071 1,116 1,176 1,224 1,302 1,323 1,428 1,512 1,519 1,581 1,666 1,674 1,736 1,764 1,836 1,953 2,108 2,142 2,232 2,499 2,604 2,646 2,856 3,038 3,162 3,213 3,332 3,348 3,528 3,672 3,689 3,906 4,216 4,284 4,557 4,743 4,998 5,208 5,292 5,859 6,076 6,324 6,426 6,664 6,696 7,378 7,497 7,812 8,568 9,114 9,486 9,996 10,584 11,067 11,718 12,152 12,648 12,852 13,671 14,229 14,756 14,994 15,624 18,228 18,972 19,992 22,134 22,491 23,436 25,704 25,823 27,342 28,458 29,512 29,988 33,201 36,456 37,944 41,013 44,268 44,982 46,872 51,646 54,684 56,916 59,976 66,402 77,469 82,026 88,536 89,964 99,603 103,292 109,368 113,832 132,804 154,938 164,052 179,928 199,206 206,584 232,407 265,608 309,876 328,104 398,412 464,814 619,752 697,221 796,824 929,628 1,394,442 1,859,256 2,788,884 and 5,577,768, with no remainder.
Since 5,577,768 cannot be divided by just 1 and 5,577,768, it is not a prime number.