A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 6329736 can be evenly divided by 1 2 3 4 6 7 8 9 12 14 18 19 21 24 28 36 38 42 56 57 63 72 76 84 114 126 133 152 168 171 228 252 266 342 399 456 504 532 661 684 798 1,064 1,197 1,322 1,368 1,596 1,983 2,394 2,644 3,192 3,966 4,627 4,788 5,288 5,949 7,932 9,254 9,576 11,898 12,559 13,881 15,864 18,508 23,796 25,118 27,762 37,016 37,677 41,643 47,592 50,236 55,524 75,354 83,286 87,913 100,472 111,048 113,031 150,708 166,572 175,826 226,062 263,739 301,416 333,144 351,652 452,124 527,478 703,304 791,217 904,248 1,054,956 1,582,434 2,109,912 3,164,868 and 6,329,736, with no remainder.
Since 6,329,736 cannot be divided by just 1 and 6,329,736, it is not a prime number.