A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1150240 can be evenly divided by 1 2 4 5 7 8 10 13 14 16 20 26 28 32 35 40 52 56 65 70 79 80 91 104 112 130 140 158 160 182 208 224 260 280 316 364 395 416 455 520 553 560 632 728 790 910 1,027 1,040 1,106 1,120 1,264 1,456 1,580 1,820 2,054 2,080 2,212 2,528 2,765 2,912 3,160 3,640 4,108 4,424 5,135 5,530 6,320 7,189 7,280 8,216 8,848 10,270 11,060 12,640 14,378 14,560 16,432 17,696 20,540 22,120 28,756 32,864 35,945 41,080 44,240 57,512 71,890 82,160 88,480 115,024 143,780 164,320 230,048 287,560 575,120 and 1,150,240, with no remainder.
Since 1,150,240 cannot be divided by just 1 and 1,150,240, it is not a prime number.