A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3353658 can be evenly divided by 1 2 3 6 7 11 14 17 21 22 33 34 42 49 51 61 66 77 98 102 119 122 147 154 183 187 231 238 294 357 366 374 427 462 539 561 671 714 833 854 1,037 1,078 1,122 1,281 1,309 1,342 1,617 1,666 2,013 2,074 2,499 2,562 2,618 2,989 3,111 3,234 3,927 4,026 4,697 4,998 5,978 6,222 7,259 7,854 8,967 9,163 9,394 11,407 14,091 14,518 17,934 18,326 21,777 22,814 27,489 28,182 32,879 34,221 43,554 50,813 54,978 65,758 68,442 79,849 98,637 101,626 152,439 159,698 197,274 239,547 304,878 479,094 558,943 1,117,886 1,676,829 and 3,353,658, with no remainder.
Since 3,353,658 cannot be divided by just 1 and 3,353,658, it is not a prime number.