A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1139880 can be evenly divided by 1 2 3 4 5 6 7 8 10 12 14 15 20 21 23 24 28 30 35 40 42 46 56 59 60 69 70 84 92 105 115 118 120 138 140 161 168 177 184 210 230 236 276 280 295 322 345 354 413 420 460 472 483 552 590 644 690 708 805 826 840 885 920 966 1,180 1,239 1,288 1,357 1,380 1,416 1,610 1,652 1,770 1,932 2,065 2,360 2,415 2,478 2,714 2,760 3,220 3,304 3,540 3,864 4,071 4,130 4,830 4,956 5,428 6,195 6,440 6,785 7,080 8,142 8,260 9,499 9,660 9,912 10,856 12,390 13,570 16,284 16,520 18,998 19,320 20,355 24,780 27,140 28,497 32,568 37,996 40,710 47,495 49,560 54,280 56,994 75,992 81,420 94,990 113,988 142,485 162,840 189,980 227,976 284,970 379,960 569,940 and 1,139,880, with no remainder.
Since 1,139,880 cannot be divided by just 1 and 1,139,880, it is not a prime number.