A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1171800 can be evenly divided by 1 2 3 4 5 6 7 8 9 10 12 14 15 18 20 21 24 25 27 28 30 31 35 36 40 42 45 50 54 56 60 62 63 70 72 75 84 90 93 100 105 108 120 124 126 135 140 150 155 168 175 180 186 189 200 210 216 217 225 248 252 270 279 280 300 310 315 350 360 372 378 420 434 450 465 504 525 540 558 600 620 630 651 675 700 744 756 775 837 840 868 900 930 945 1,050 1,080 1,085 1,116 1,240 1,260 1,302 1,350 1,395 1,400 1,512 1,550 1,575 1,674 1,736 1,800 1,860 1,890 1,953 2,100 2,170 2,232 2,325 2,520 2,604 2,700 2,790 3,100 3,150 3,255 3,348 3,720 3,780 3,906 4,185 4,200 4,340 4,650 4,725 5,208 5,400 5,425 5,580 5,859 6,200 6,300 6,510 6,696 6,975 7,560 7,812 8,370 8,680 9,300 9,450 9,765 10,850 11,160 11,718 12,600 13,020 13,950 15,624 16,275 16,740 18,600 18,900 19,530 20,925 21,700 23,436 26,040 27,900 29,295 32,550 33,480 37,800 39,060 41,850 43,400 46,872 48,825 55,800 58,590 65,100 78,120 83,700 97,650 117,180 130,200 146,475 167,400 195,300 234,360 292,950 390,600 585,900 and 1,171,800, with no remainder.
Since 1,171,800 cannot be divided by just 1 and 1,171,800, it is not a prime number.