use Math::BaseCalc;

my $bc = Math::BaseCalc::new( 
    digits=> [ 'A' .. 'Z', 'a' .. 'z', 2 .. 9 ]
);
print $bc->to_base( 99999999 ); # Corrected 
Hq7un

print $bc->from_base( 'Hq7un' ); # Corrected
99999999