A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1229580 can be evenly divided by 1 2 3 4 5 6 9 10 11 12 15 18 20 22 23 27 30 33 36 44 45 46 54 55 60 66 69 81 90 92 99 108 110 115 132 135 138 162 165 180 198 207 220 230 243 253 270 276 297 324 330 345 396 405 414 460 486 495 506 540 594 621 660 690 759 810 828 891 972 990 1,012 1,035 1,188 1,215 1,242 1,265 1,380 1,485 1,518 1,620 1,782 1,863 1,980 2,070 2,277 2,430 2,484 2,530 2,673 2,970 3,036 3,105 3,564 3,726 3,795 4,140 4,455 4,554 4,860 5,060 5,346 5,589 5,940 6,210 6,831 7,452 7,590 8,910 9,108 9,315 10,692 11,178 11,385 12,420 13,365 13,662 15,180 17,820 18,630 20,493 22,356 22,770 26,730 27,324 27,945 34,155 37,260 40,986 45,540 53,460 55,890 61,479 68,310 81,972 102,465 111,780 122,958 136,620 204,930 245,916 307,395 409,860 614,790 and 1,229,580, with no remainder.
Since 1,229,580 cannot be divided by just 1 and 1,229,580, it is not a prime number.