A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1540080 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 16 18 20 23 24 27 30 31 36 40 45 46 48 54 60 62 69 72 80 90 92 93 108 115 120 124 135 138 144 155 180 184 186 207 216 230 240 248 270 276 279 310 345 360 368 372 414 432 460 465 496 540 552 558 620 621 690 713 720 744 828 837 920 930 1,035 1,080 1,104 1,116 1,240 1,242 1,380 1,395 1,426 1,488 1,656 1,674 1,840 1,860 2,070 2,139 2,160 2,232 2,480 2,484 2,760 2,790 2,852 3,105 3,312 3,348 3,565 3,720 4,140 4,185 4,278 4,464 4,968 5,520 5,580 5,704 6,210 6,417 6,696 7,130 7,440 8,280 8,370 8,556 9,936 10,695 11,160 11,408 12,420 12,834 13,392 14,260 16,560 16,740 17,112 19,251 21,390 22,320 24,840 25,668 28,520 32,085 33,480 34,224 38,502 42,780 49,680 51,336 57,040 64,170 66,960 77,004 85,560 96,255 102,672 128,340 154,008 171,120 192,510 256,680 308,016 385,020 513,360 770,040 and 1,540,080, with no remainder.
Since 1,540,080 cannot be divided by just 1 and 1,540,080, it is not a prime number.