It's ugly, not golfy, and not fast, but that's the best I could come up with: 
my $number="8i8jkwdz4fks4d1z";
chg(1);
sub chg{(substr($number,-1*$_[0],1)=dig(substr($number,-1*$_[0],1))) e
+q '0' and chg($_[0]+1)}
sub dig{my $d=shift; if($d==9){return 'a'}elsif($d=~/\d/){return $d+1}
+elsif(lc($d) eq 'z'){return 0}else{return chr(ord($d)+1)}}
print $number;

[download]

In reply to Re: Base36 numbers: speed and golf by Ido
in thread Base36 numbers: speed and golf by nop

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.