A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 5588856 can be evenly divided by 1 2 3 4 6 7 8 9 12 13 14 18 21 24 26 28 36 39 42 52 56 63 72 78 84 91 104 117 126 156 168 182 234 252 273 312 364 468 504 546 728 819 853 936 1,092 1,638 1,706 2,184 2,559 3,276 3,412 5,118 5,971 6,552 6,824 7,677 10,236 11,089 11,942 15,354 17,913 20,472 22,178 23,884 30,708 33,267 35,826 44,356 47,768 53,739 61,416 66,534 71,652 77,623 88,712 99,801 107,478 133,068 143,304 155,246 199,602 214,956 232,869 266,136 310,492 399,204 429,912 465,738 620,984 698,607 798,408 931,476 1,397,214 1,862,952 2,794,428 and 5,588,856, with no remainder.
Since 5,588,856 cannot be divided by just 1 and 5,588,856, it is not a prime number.