A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 902400 can be evenly divided by 1 2 3 4 5 6 8 10 12 15 16 20 24 25 30 32 40 47 48 50 60 64 75 80 94 96 100 120 128 141 150 160 188 192 200 235 240 256 282 300 320 376 384 400 470 480 564 600 640 705 752 768 800 940 960 1,128 1,175 1,200 1,280 1,410 1,504 1,600 1,880 1,920 2,256 2,350 2,400 2,820 3,008 3,200 3,525 3,760 3,840 4,512 4,700 4,800 5,640 6,016 6,400 7,050 7,520 9,024 9,400 9,600 11,280 12,032 14,100 15,040 18,048 18,800 19,200 22,560 28,200 30,080 36,096 37,600 45,120 56,400 60,160 75,200 90,240 112,800 150,400 180,480 225,600 300,800 451,200 and 902,400, with no remainder.
Since 902,400 cannot be divided by just 1 and 902,400, it is not a prime number.