A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 324000 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 16 18 20 24 25 27 30 32 36 40 45 48 50 54 60 72 75 80 81 90 96 100 108 120 125 135 144 150 160 162 180 200 216 225 240 250 270 288 300 324 360 375 400 405 432 450 480 500 540 600 648 675 720 750 800 810 864 900 1,000 1,080 1,125 1,200 1,296 1,350 1,440 1,500 1,620 1,800 2,000 2,025 2,160 2,250 2,400 2,592 2,700 3,000 3,240 3,375 3,600 4,000 4,050 4,320 4,500 5,400 6,000 6,480 6,750 7,200 8,100 9,000 10,125 10,800 12,000 12,960 13,500 16,200 18,000 20,250 21,600 27,000 32,400 36,000 40,500 54,000 64,800 81,000 108,000 162,000 and 324,000, with no remainder.
Since 324,000 cannot be divided by just 1 and 324,000, it is not a prime number.