A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 910560 can be evenly divided by 1 2 3 4 5 6 7 8 10 12 14 15 16 20 21 24 28 30 32 35 40 42 48 56 60 70 80 84 96 105 112 120 140 160 168 210 224 240 271 280 336 420 480 542 560 672 813 840 1,084 1,120 1,355 1,626 1,680 1,897 2,168 2,710 3,252 3,360 3,794 4,065 4,336 5,420 5,691 6,504 7,588 8,130 8,672 9,485 10,840 11,382 13,008 15,176 16,260 18,970 21,680 22,764 26,016 28,455 30,352 32,520 37,940 43,360 45,528 56,910 60,704 65,040 75,880 91,056 113,820 130,080 151,760 182,112 227,640 303,520 455,280 and 910,560, with no remainder.
Since 910,560 cannot be divided by just 1 and 910,560, it is not a prime number.