A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2342400 can be evenly divided by 1 2 3 4 5 6 8 10 12 15 16 20 24 25 30 32 40 48 50 60 61 64 75 80 96 100 120 122 128 150 160 183 192 200 240 244 256 300 305 320 366 384 400 480 488 512 600 610 640 732 768 800 915 960 976 1,200 1,220 1,280 1,464 1,525 1,536 1,600 1,830 1,920 1,952 2,400 2,440 2,560 2,928 3,050 3,200 3,660 3,840 3,904 4,575 4,800 4,880 5,856 6,100 6,400 7,320 7,680 7,808 9,150 9,600 9,760 11,712 12,200 12,800 14,640 15,616 18,300 19,200 19,520 23,424 24,400 29,280 31,232 36,600 38,400 39,040 46,848 48,800 58,560 73,200 78,080 93,696 97,600 117,120 146,400 156,160 195,200 234,240 292,800 390,400 468,480 585,600 780,800 1,171,200 and 2,342,400, with no remainder.
Since 2,342,400 cannot be divided by just 1 and 2,342,400, it is not a prime number.