A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1341600 can be evenly divided by 1 2 3 4 5 6 8 10 12 13 15 16 20 24 25 26 30 32 39 40 43 48 50 52 60 65 75 78 80 86 96 100 104 120 129 130 150 156 160 172 195 200 208 215 240 258 260 300 312 325 344 390 400 416 430 480 516 520 559 600 624 645 650 688 780 800 860 975 1,032 1,040 1,075 1,118 1,200 1,248 1,290 1,300 1,376 1,560 1,677 1,720 1,950 2,064 2,080 2,150 2,236 2,400 2,580 2,600 2,795 3,120 3,225 3,354 3,440 3,900 4,128 4,300 4,472 5,160 5,200 5,590 6,240 6,450 6,708 6,880 7,800 8,385 8,600 8,944 10,320 10,400 11,180 12,900 13,416 13,975 15,600 16,770 17,200 17,888 20,640 22,360 25,800 26,832 27,950 31,200 33,540 34,400 41,925 44,720 51,600 53,664 55,900 67,080 83,850 89,440 103,200 111,800 134,160 167,700 223,600 268,320 335,400 447,200 670,800 and 1,341,600, with no remainder.
Since 1,341,600 cannot be divided by just 1 and 1,341,600, it is not a prime number.