A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3763188 can be evenly divided by 1 2 3 4 6 9 11 12 13 17 18 22 26 33 34 36 39 43 44 51 52 66 68 78 86 99 102 117 129 132 143 153 156 172 187 198 204 221 234 258 286 306 374 387 396 429 442 468 473 516 559 561 572 612 663 731 748 774 858 884 946 1,118 1,122 1,287 1,326 1,419 1,462 1,548 1,677 1,683 1,716 1,892 1,989 2,193 2,236 2,244 2,431 2,574 2,652 2,838 2,924 3,354 3,366 3,978 4,257 4,386 4,862 5,031 5,148 5,676 6,149 6,579 6,708 6,732 7,293 7,956 8,041 8,514 8,772 9,503 9,724 10,062 12,298 13,158 14,586 16,082 17,028 18,447 19,006 20,124 21,879 24,123 24,596 26,316 28,509 29,172 32,164 36,894 38,012 43,758 48,246 55,341 57,018 72,369 73,788 85,527 87,516 96,492 104,533 110,682 114,036 144,738 171,054 209,066 221,364 289,476 313,599 342,108 418,132 627,198 940,797 1,254,396 1,881,594 and 3,763,188, with no remainder.
Since 3,763,188 cannot be divided by just 1 and 3,763,188, it is not a prime number.