A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 634500 can be evenly divided by 1 2 3 4 5 6 9 10 12 15 18 20 25 27 30 36 45 47 50 54 60 75 90 94 100 108 125 135 141 150 180 188 225 235 250 270 282 300 375 423 450 470 500 540 564 675 705 750 846 900 940 1,125 1,175 1,269 1,350 1,410 1,500 1,692 2,115 2,250 2,350 2,538 2,700 2,820 3,375 3,525 4,230 4,500 4,700 5,076 5,875 6,345 6,750 7,050 8,460 10,575 11,750 12,690 13,500 14,100 17,625 21,150 23,500 25,380 31,725 35,250 42,300 52,875 63,450 70,500 105,750 126,900 158,625 211,500 317,250 and 634,500, with no remainder.
Since 634,500 cannot be divided by just 1 and 634,500, it is not a prime number.