A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 632400 can be evenly divided by 1 2 3 4 5 6 8 10 12 15 16 17 20 24 25 30 31 34 40 48 50 51 60 62 68 75 80 85 93 100 102 120 124 136 150 155 170 186 200 204 240 248 255 272 300 310 340 372 400 408 425 465 496 510 527 600 620 680 744 775 816 850 930 1,020 1,054 1,200 1,240 1,275 1,360 1,488 1,550 1,581 1,700 1,860 2,040 2,108 2,325 2,480 2,550 2,635 3,100 3,162 3,400 3,720 4,080 4,216 4,650 5,100 5,270 6,200 6,324 6,800 7,440 7,905 8,432 9,300 10,200 10,540 12,400 12,648 13,175 15,810 18,600 20,400 21,080 25,296 26,350 31,620 37,200 39,525 42,160 52,700 63,240 79,050 105,400 126,480 158,100 210,800 316,200 and 632,400, with no remainder.
Since 632,400 cannot be divided by just 1 and 632,400, it is not a prime number.