A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1770120 can be evenly divided by 1 2 3 4 5 6 8 9 10 11 12 15 18 20 22 24 27 30 33 36 40 44 45 54 55 60 66 72 88 90 99 108 110 120 132 135 149 165 180 198 216 220 264 270 297 298 330 360 396 440 447 495 540 594 596 660 745 792 894 990 1,080 1,188 1,192 1,320 1,341 1,485 1,490 1,639 1,788 1,980 2,235 2,376 2,682 2,970 2,980 3,278 3,576 3,960 4,023 4,470 4,917 5,364 5,940 5,960 6,556 6,705 8,046 8,195 8,940 9,834 10,728 11,880 13,112 13,410 14,751 16,092 16,390 17,880 19,668 20,115 24,585 26,820 29,502 32,184 32,780 39,336 40,230 44,253 49,170 53,640 59,004 65,560 73,755 80,460 88,506 98,340 118,008 147,510 160,920 177,012 196,680 221,265 295,020 354,024 442,530 590,040 885,060 and 1,770,120, with no remainder.
Since 1,770,120 cannot be divided by just 1 and 1,770,120, it is not a prime number.