A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2903472 can be evenly divided by 1 2 3 4 6 8 9 11 12 13 16 18 22 24 26 27 33 36 39 44 47 48 52 54 66 72 78 88 94 99 104 108 117 132 141 143 144 156 176 188 198 208 216 234 264 282 286 297 312 351 376 396 423 429 432 468 517 528 564 572 594 611 624 702 752 792 846 858 936 1,034 1,128 1,144 1,188 1,222 1,269 1,287 1,404 1,551 1,584 1,692 1,716 1,833 1,872 2,068 2,256 2,288 2,376 2,444 2,538 2,574 2,808 3,102 3,384 3,432 3,666 3,861 4,136 4,653 4,752 4,888 5,076 5,148 5,499 5,616 6,204 6,721 6,768 6,864 7,332 7,722 8,272 9,306 9,776 10,152 10,296 10,998 12,408 13,442 13,959 14,664 15,444 16,497 18,612 20,163 20,304 20,592 21,996 24,816 26,884 27,918 29,328 30,888 32,994 37,224 40,326 43,992 53,768 55,836 60,489 61,776 65,988 74,448 80,652 87,984 107,536 111,672 120,978 131,976 161,304 181,467 223,344 241,956 263,952 322,608 362,934 483,912 725,868 967,824 1,451,736 and 2,903,472, with no remainder.
Since 2,903,472 cannot be divided by just 1 and 2,903,472, it is not a prime number.