A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 9728264 can be evenly divided by 1 2 4 7 8 13 14 23 26 28 46 49 52 56 83 91 92 98 104 161 166 182 184 196 299 322 332 364 392 581 598 637 644 664 728 1,079 1,127 1,162 1,196 1,274 1,288 1,909 2,093 2,158 2,254 2,324 2,392 2,548 3,818 4,067 4,186 4,316 4,508 4,648 5,096 7,553 7,636 8,134 8,372 8,632 9,016 13,363 14,651 15,106 15,272 16,268 16,744 24,817 26,726 29,302 30,212 32,536 49,634 52,871 53,452 58,604 60,424 93,541 99,268 105,742 106,904 117,208 173,719 187,082 198,536 211,484 347,438 374,164 422,968 694,876 748,328 1,216,033 1,389,752 2,432,066 4,864,132 and 9,728,264, with no remainder.
Since 9,728,264 cannot be divided by just 1 and 9,728,264, it is not a prime number.