A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 898560 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 13 15 16 18 20 24 26 27 30 32 36 39 40 45 48 52 54 60 64 65 72 78 80 90 96 104 108 117 120 128 130 135 144 156 160 180 192 195 208 216 234 240 256 260 270 288 312 320 351 360 384 390 416 432 468 480 512 520 540 576 585 624 640 702 720 768 780 832 864 936 960 1,040 1,080 1,152 1,170 1,248 1,280 1,404 1,440 1,536 1,560 1,664 1,728 1,755 1,872 1,920 2,080 2,160 2,304 2,340 2,496 2,560 2,808 2,880 3,120 3,328 3,456 3,510 3,744 3,840 4,160 4,320 4,608 4,680 4,992 5,616 5,760 6,240 6,656 6,912 7,020 7,488 7,680 8,320 8,640 9,360 9,984 11,232 11,520 12,480 13,824 14,040 14,976 16,640 17,280 18,720 19,968 22,464 23,040 24,960 28,080 29,952 33,280 34,560 37,440 44,928 49,920 56,160 59,904 69,120 74,880 89,856 99,840 112,320 149,760 179,712 224,640 299,520 449,280 and 898,560, with no remainder.
Since 898,560 cannot be divided by just 1 and 898,560, it is not a prime number.