A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2748600 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 18 20 24 25 27 30 36 40 45 50 54 60 72 75 90 100 108 120 135 150 180 200 216 225 270 300 360 450 509 540 600 675 900 1,018 1,080 1,350 1,527 1,800 2,036 2,545 2,700 3,054 4,072 4,581 5,090 5,400 6,108 7,635 9,162 10,180 12,216 12,725 13,743 15,270 18,324 20,360 22,905 25,450 27,486 30,540 36,648 38,175 45,810 50,900 54,972 61,080 68,715 76,350 91,620 101,800 109,944 114,525 137,430 152,700 183,240 229,050 274,860 305,400 343,575 458,100 549,720 687,150 916,200 1,374,300 and 2,748,600, with no remainder.
Since 2,748,600 cannot be divided by just 1 and 2,748,600, it is not a prime number.