A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1569750 can be evenly divided by 1 2 3 5 6 7 10 13 14 15 21 23 25 26 30 35 39 42 46 50 65 69 70 75 78 91 105 115 125 130 138 150 161 175 182 195 210 230 250 273 299 322 325 345 350 375 390 455 483 525 546 575 598 650 690 750 805 875 897 910 966 975 1,050 1,150 1,365 1,495 1,610 1,625 1,725 1,750 1,794 1,950 2,093 2,275 2,415 2,625 2,730 2,875 2,990 3,250 3,450 4,025 4,186 4,485 4,550 4,830 4,875 5,250 5,750 6,279 6,825 7,475 8,050 8,625 8,970 9,750 10,465 11,375 12,075 12,558 13,650 14,950 17,250 20,125 20,930 22,425 22,750 24,150 31,395 34,125 37,375 40,250 44,850 52,325 60,375 62,790 68,250 74,750 104,650 112,125 120,750 156,975 224,250 261,625 313,950 523,250 784,875 and 1,569,750, with no remainder.
Since 1,569,750 cannot be divided by just 1 and 1,569,750, it is not a prime number.