A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 8307712 can be evenly divided by 1 2 4 7 8 14 16 19 28 32 38 56 61 64 76 112 122 128 133 152 224 244 256 266 304 427 448 488 512 532 608 854 896 976 1,024 1,064 1,159 1,216 1,708 1,792 1,952 2,128 2,318 2,432 3,416 3,584 3,904 4,256 4,636 4,864 6,832 7,168 7,808 8,113 8,512 9,272 9,728 13,664 15,616 16,226 17,024 18,544 19,456 27,328 31,232 32,452 34,048 37,088 54,656 62,464 64,904 68,096 74,176 109,312 129,808 136,192 148,352 218,624 259,616 296,704 437,248 519,232 593,408 1,038,464 1,186,816 2,076,928 4,153,856 and 8,307,712, with no remainder.
Since 8,307,712 cannot be divided by just 1 and 8,307,712, it is not a prime number.