A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1053000 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 13 15 18 20 24 25 26 27 30 36 39 40 45 50 52 54 60 65 72 75 78 81 90 100 104 108 117 120 125 130 135 150 156 162 180 195 200 216 225 234 250 260 270 300 312 324 325 351 360 375 390 405 450 468 500 520 540 585 600 648 650 675 702 750 780 810 900 936 975 1,000 1,053 1,080 1,125 1,170 1,300 1,350 1,404 1,500 1,560 1,620 1,625 1,755 1,800 1,950 2,025 2,106 2,250 2,340 2,600 2,700 2,808 2,925 3,000 3,240 3,250 3,375 3,510 3,900 4,050 4,212 4,500 4,680 4,875 5,265 5,400 5,850 6,500 6,750 7,020 7,800 8,100 8,424 8,775 9,000 9,750 10,125 10,530 11,700 13,000 13,500 14,040 14,625 16,200 17,550 19,500 20,250 21,060 23,400 26,325 27,000 29,250 35,100 39,000 40,500 42,120 43,875 52,650 58,500 70,200 81,000 87,750 105,300 117,000 131,625 175,500 210,600 263,250 351,000 526,500 and 1,053,000, with no remainder.
Since 1,053,000 cannot be divided by just 1 and 1,053,000, it is not a prime number.