A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3266676 can be evenly divided by 1 2 3 4 6 7 9 12 14 18 21 27 28 29 36 42 54 58 63 84 87 108 116 126 149 174 189 203 252 261 298 348 378 406 447 522 596 609 756 783 812 894 1,043 1,044 1,218 1,341 1,566 1,788 1,827 2,086 2,436 2,682 3,129 3,132 3,654 4,023 4,172 4,321 5,364 5,481 6,258 7,308 8,046 8,642 9,387 10,962 12,516 12,963 16,092 17,284 18,774 21,924 25,926 28,161 30,247 37,548 38,889 51,852 56,322 60,494 77,778 90,741 112,644 116,667 120,988 155,556 181,482 233,334 272,223 362,964 466,668 544,446 816,669 1,088,892 1,633,338 and 3,266,676, with no remainder.
Since 3,266,676 cannot be divided by just 1 and 3,266,676, it is not a prime number.