A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 5486376 can be evenly divided by 1 2 3 4 6 7 8 12 14 17 21 24 28 34 42 51 56 68 84 102 113 119 136 168 204 226 238 289 339 357 408 452 476 578 678 714 791 867 904 952 1,156 1,356 1,428 1,582 1,734 1,921 2,023 2,312 2,373 2,712 2,856 3,164 3,468 3,842 4,046 4,746 5,763 6,069 6,328 6,936 7,684 8,092 9,492 11,526 12,138 13,447 15,368 16,184 18,984 23,052 24,276 26,894 32,657 40,341 46,104 48,552 53,788 65,314 80,682 97,971 107,576 130,628 161,364 195,942 228,599 261,256 322,728 391,884 457,198 685,797 783,768 914,396 1,371,594 1,828,792 2,743,188 and 5,486,376, with no remainder.
Since 5,486,376 cannot be divided by just 1 and 5,486,376, it is not a prime number.