A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 594000 can be evenly divided by 1 2 3 4 5 6 8 9 10 11 12 15 16 18 20 22 24 25 27 30 33 36 40 44 45 48 50 54 55 60 66 72 75 80 88 90 99 100 108 110 120 125 132 135 144 150 165 176 180 198 200 216 220 225 240 250 264 270 275 297 300 330 360 375 396 400 432 440 450 495 500 528 540 550 594 600 660 675 720 750 792 825 880 900 990 1,000 1,080 1,100 1,125 1,188 1,200 1,320 1,350 1,375 1,485 1,500 1,584 1,650 1,800 1,980 2,000 2,160 2,200 2,250 2,376 2,475 2,640 2,700 2,750 2,970 3,000 3,300 3,375 3,600 3,960 4,125 4,400 4,500 4,752 4,950 5,400 5,500 5,940 6,000 6,600 6,750 7,425 7,920 8,250 9,000 9,900 10,800 11,000 11,880 12,375 13,200 13,500 14,850 16,500 18,000 19,800 22,000 23,760 24,750 27,000 29,700 33,000 37,125 39,600 49,500 54,000 59,400 66,000 74,250 99,000 118,800 148,500 198,000 297,000 and 594,000, with no remainder.
Since 594,000 cannot be divided by just 1 and 594,000, it is not a prime number.