A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 487620 can be evenly divided by 1 2 3 4 5 6 7 9 10 12 14 15 18 20 21 27 28 30 35 36 42 43 45 54 60 63 70 81 84 86 90 105 108 126 129 135 140 162 172 180 189 210 215 252 258 270 301 315 324 378 387 405 420 430 516 540 567 602 630 645 756 774 810 860 903 945 1,134 1,161 1,204 1,260 1,290 1,505 1,548 1,620 1,806 1,890 1,935 2,268 2,322 2,580 2,709 2,835 3,010 3,483 3,612 3,780 3,870 4,515 4,644 5,418 5,670 5,805 6,020 6,966 7,740 8,127 9,030 10,836 11,340 11,610 13,545 13,932 16,254 17,415 18,060 23,220 24,381 27,090 32,508 34,830 40,635 48,762 54,180 69,660 81,270 97,524 121,905 162,540 243,810 and 487,620, with no remainder.
Since 487,620 cannot be divided by just 1 and 487,620, it is not a prime number.