A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1318200 can be evenly divided by 1 2 3 4 5 6 8 10 12 13 15 20 24 25 26 30 39 40 50 52 60 65 75 78 100 104 120 130 150 156 169 195 200 260 300 312 325 338 390 507 520 600 650 676 780 845 975 1,014 1,300 1,352 1,560 1,690 1,950 2,028 2,197 2,535 2,600 3,380 3,900 4,056 4,225 4,394 5,070 6,591 6,760 7,800 8,450 8,788 10,140 10,985 12,675 13,182 16,900 17,576 20,280 21,970 25,350 26,364 32,955 33,800 43,940 50,700 52,728 54,925 65,910 87,880 101,400 109,850 131,820 164,775 219,700 263,640 329,550 439,400 659,100 and 1,318,200, with no remainder.
Since 1,318,200 cannot be divided by just 1 and 1,318,200, it is not a prime number.