A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1896000 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 64 75 79 80 96 100 120 125 150 158 160 192 200 237 240 250 300 316 320 375 395 400 474 480 500 600 632 750 790 800 948 960 1,000 1,185 1,200 1,264 1,500 1,580 1,600 1,896 1,975 2,000 2,370 2,400 2,528 3,000 3,160 3,792 3,950 4,000 4,740 4,800 5,056 5,925 6,000 6,320 7,584 7,900 8,000 9,480 9,875 11,850 12,000 12,640 15,168 15,800 18,960 19,750 23,700 24,000 25,280 29,625 31,600 37,920 39,500 47,400 59,250 63,200 75,840 79,000 94,800 118,500 126,400 158,000 189,600 237,000 316,000 379,200 474,000 632,000 948,000 and 1,896,000, with no remainder.
Since 1,896,000 cannot be divided by just 1 and 1,896,000, it is not a prime number.