A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4358508 can be evenly divided by 1 2 3 4 6 7 11 12 14 21 22 28 33 42 44 53 66 77 84 89 106 132 154 159 178 212 231 267 308 318 356 371 462 534 583 623 636 742 924 979 1,068 1,113 1,166 1,246 1,484 1,749 1,869 1,958 2,226 2,332 2,492 2,937 3,498 3,738 3,916 4,081 4,452 4,717 5,874 6,853 6,996 7,476 8,162 9,434 11,748 12,243 13,706 14,151 16,324 18,868 20,559 24,486 27,412 28,302 33,019 41,118 48,972 51,887 56,604 66,038 82,236 99,057 103,774 132,076 155,661 198,114 207,548 311,322 363,209 396,228 622,644 726,418 1,089,627 1,452,836 2,179,254 and 4,358,508, with no remainder.
Since 4,358,508 cannot be divided by just 1 and 4,358,508, it is not a prime number.