A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2552000 can be evenly divided by 1 2 4 5 8 10 11 16 20 22 25 29 32 40 44 50 55 58 64 80 88 100 110 116 125 145 160 176 200 220 232 250 275 290 319 320 352 400 440 464 500 550 580 638 704 725 800 880 928 1,000 1,100 1,160 1,276 1,375 1,450 1,595 1,600 1,760 1,856 2,000 2,200 2,320 2,552 2,750 2,900 3,190 3,520 3,625 4,000 4,400 4,640 5,104 5,500 5,800 6,380 7,250 7,975 8,000 8,800 9,280 10,208 11,000 11,600 12,760 14,500 15,950 17,600 20,416 22,000 23,200 25,520 29,000 31,900 39,875 44,000 46,400 51,040 58,000 63,800 79,750 88,000 102,080 116,000 127,600 159,500 232,000 255,200 319,000 510,400 638,000 1,276,000 and 2,552,000, with no remainder.
Since 2,552,000 cannot be divided by just 1 and 2,552,000, it is not a prime number.