A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 3892860 can be evenly divided by 1 2 3 4 5 6 9 10 12 15 18 20 27 30 36 45 54 60 81 89 90 108 135 162 178 180 243 267 270 324 356 405 445 486 534 540 729 801 810 890 972 1,068 1,215 1,335 1,458 1,602 1,620 1,780 2,187 2,403 2,430 2,670 2,916 3,204 3,645 4,005 4,374 4,806 4,860 5,340 7,209 7,290 8,010 8,748 9,612 10,935 12,015 14,418 14,580 16,020 21,627 21,870 24,030 28,836 36,045 43,254 43,740 48,060 64,881 72,090 86,508 108,135 129,762 144,180 194,643 216,270 259,524 324,405 389,286 432,540 648,810 778,572 973,215 1,297,620 1,946,430 and 3,892,860, with no remainder.
Since 3,892,860 cannot be divided by just 1 and 3,892,860, it is not a prime number.