A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1573000 can be evenly divided by 1 2 4 5 8 10 11 13 20 22 25 26 40 44 50 52 55 65 88 100 104 110 121 125 130 143 200 220 242 250 260 275 286 325 440 484 500 520 550 572 605 650 715 968 1,000 1,100 1,144 1,210 1,300 1,375 1,430 1,573 1,625 2,200 2,420 2,600 2,750 2,860 3,025 3,146 3,250 3,575 4,840 5,500 5,720 6,050 6,292 6,500 7,150 7,865 11,000 12,100 12,584 13,000 14,300 15,125 15,730 17,875 24,200 28,600 30,250 31,460 35,750 39,325 60,500 62,920 71,500 78,650 121,000 143,000 157,300 196,625 314,600 393,250 786,500 and 1,573,000, with no remainder.
Since 1,573,000 cannot be divided by just 1 and 1,573,000, it is not a prime number.