A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 956800 can be evenly divided by 1 2 4 5 8 10 13 16 20 23 25 26 32 40 46 50 52 64 65 80 92 100 104 115 128 130 160 184 200 208 230 260 299 320 325 368 400 416 460 520 575 598 640 650 736 800 832 920 1,040 1,150 1,196 1,300 1,472 1,495 1,600 1,664 1,840 2,080 2,300 2,392 2,600 2,944 2,990 3,200 3,680 4,160 4,600 4,784 5,200 5,980 7,360 7,475 8,320 9,200 9,568 10,400 11,960 14,720 14,950 18,400 19,136 20,800 23,920 29,900 36,800 38,272 41,600 47,840 59,800 73,600 95,680 119,600 191,360 239,200 478,400 and 956,800, with no remainder.
Since 956,800 cannot be divided by just 1 and 956,800, it is not a prime number.