A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2459600 can be evenly divided by 1 2 4 5 8 10 11 13 16 20 22 25 26 40 43 44 50 52 55 65 80 86 88 100 104 110 130 143 172 176 200 208 215 220 260 275 286 325 344 400 430 440 473 520 550 559 572 650 688 715 860 880 946 1,040 1,075 1,100 1,118 1,144 1,300 1,430 1,720 1,892 2,150 2,200 2,236 2,288 2,365 2,600 2,795 2,860 3,440 3,575 3,784 4,300 4,400 4,472 4,730 5,200 5,590 5,720 6,149 7,150 7,568 8,600 8,944 9,460 11,180 11,440 11,825 12,298 13,975 14,300 17,200 18,920 22,360 23,650 24,596 27,950 28,600 30,745 37,840 44,720 47,300 49,192 55,900 57,200 61,490 94,600 98,384 111,800 122,980 153,725 189,200 223,600 245,960 307,450 491,920 614,900 1,229,800 and 2,459,600, with no remainder.
Since 2,459,600 cannot be divided by just 1 and 2,459,600, it is not a prime number.