A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1827540 can be evenly divided by 1 2 3 4 5 6 9 10 11 12 13 15 18 20 22 26 30 33 36 39 44 45 52 55 60 65 66 71 78 90 99 110 117 130 132 142 143 156 165 180 195 198 213 220 234 260 284 286 330 355 390 396 426 429 468 495 572 585 639 660 710 715 780 781 852 858 923 990 1,065 1,170 1,278 1,287 1,420 1,430 1,562 1,716 1,846 1,980 2,130 2,145 2,340 2,343 2,556 2,574 2,769 2,860 3,124 3,195 3,692 3,905 4,260 4,290 4,615 4,686 5,148 5,538 6,390 6,435 7,029 7,810 8,307 8,580 9,230 9,372 10,153 11,076 11,715 12,780 12,870 13,845 14,058 15,620 16,614 18,460 20,306 23,430 25,740 27,690 28,116 30,459 33,228 35,145 40,612 41,535 46,860 50,765 55,380 60,918 70,290 83,070 91,377 101,530 121,836 140,580 152,295 166,140 182,754 203,060 304,590 365,508 456,885 609,180 913,770 and 1,827,540, with no remainder.
Since 1,827,540 cannot be divided by just 1 and 1,827,540, it is not a prime number.