A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1451736 can be evenly divided by 1 2 3 4 6 8 9 11 12 13 18 22 24 26 27 33 36 39 44 47 52 54 66 72 78 88 94 99 104 108 117 132 141 143 156 188 198 216 234 264 282 286 297 312 351 376 396 423 429 468 517 564 572 594 611 702 792 846 858 936 1,034 1,128 1,144 1,188 1,222 1,269 1,287 1,404 1,551 1,692 1,716 1,833 2,068 2,376 2,444 2,538 2,574 2,808 3,102 3,384 3,432 3,666 3,861 4,136 4,653 4,888 5,076 5,148 5,499 6,204 6,721 7,332 7,722 9,306 10,152 10,296 10,998 12,408 13,442 13,959 14,664 15,444 16,497 18,612 20,163 21,996 26,884 27,918 30,888 32,994 37,224 40,326 43,992 53,768 55,836 60,489 65,988 80,652 111,672 120,978 131,976 161,304 181,467 241,956 362,934 483,912 725,868 and 1,451,736, with no remainder.
Since 1,451,736 cannot be divided by just 1 and 1,451,736, it is not a prime number.