A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2861600 can be evenly divided by 1 2 4 5 7 8 10 14 16 20 25 28 32 35 40 49 50 56 70 73 80 98 100 112 140 146 160 175 196 200 224 245 280 292 350 365 392 400 490 511 560 584 700 730 784 800 980 1,022 1,120 1,168 1,225 1,400 1,460 1,568 1,825 1,960 2,044 2,336 2,450 2,555 2,800 2,920 3,577 3,650 3,920 4,088 4,900 5,110 5,600 5,840 7,154 7,300 7,840 8,176 9,800 10,220 11,680 12,775 14,308 14,600 16,352 17,885 19,600 20,440 25,550 28,616 29,200 35,770 39,200 40,880 51,100 57,232 58,400 71,540 81,760 89,425 102,200 114,464 143,080 178,850 204,400 286,160 357,700 408,800 572,320 715,400 1,430,800 and 2,861,600, with no remainder.
Since 2,861,600 cannot be divided by just 1 and 2,861,600, it is not a prime number.