A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 6298425 can be evenly divided by 1 3 5 7 9 15 21 25 27 31 35 43 45 63 75 93 105 129 135 155 175 189 215 217 225 279 301 315 387 465 525 645 651 675 775 837 903 945 1,075 1,085 1,161 1,333 1,395 1,505 1,575 1,935 1,953 2,325 2,709 3,225 3,255 3,999 4,185 4,515 4,725 5,425 5,805 5,859 6,665 6,975 7,525 8,127 9,331 9,675 9,765 11,997 13,545 16,275 19,995 20,925 22,575 27,993 29,025 29,295 33,325 35,991 40,635 46,655 48,825 59,985 67,725 83,979 99,975 139,965 146,475 179,955 203,175 233,275 251,937 299,925 419,895 699,825 899,775 1,259,685 2,099,475 and 6,298,425, with no remainder.
Since 6,298,425 cannot be divided by just 1 and 6,298,425, it is not a prime number.