Given that it does not report 33 as rotatable I don't see your point. Also the digits 347 are not stripped, they are replaced with the digit 6, see the man for tr. It would not actually matter if they were stripped or replaced the original value will not be equal to the reversed value.

sub is_rotatable{
#234567890123456789012345678901234567
$_=$_[0];y/2569347/5296/;pop==reverse
}

for my $i(3,33,131,141,171,25696925,101,88) {
    printf "%s %s rotatable\n", $i, is_rotatable( $i ) ? 'is' : 'not'
}

__DATA__
3 not rotatable
33 not rotatable
131 not rotatable
141 not rotatable
171 not rotatable
25696925 is rotatable
101 is rotatable
88 is rotatable
[download]

I found the problem. It had to do with the fact that your version doesn't respect $_, while mine does.

sub r2{
$_=$_[0];y/2569347/5296/;pop==reverse
}

my @tests = (0..9);
print "$_: ",(r2($_)?'Yes':'No'), "\n" for @tests;

__DATA__
0: Yes
1: Yes
2: Yes
3: Yes
4: Yes
5: Yes
6: Yes
7: Yes
8: Yes
9: Yes
[download]

Because of the way I was calling your function, I saw something wrong. However, I mistook what I saw wrong and I apologize for not knowing tr/// as well as I should have.

------
We are the carpenters and bricklayers of the Information Age.

Then there are Damian modules.... *sigh* ... that's not about being less-lazy -- that's about being on some really good drugs -- you know, there is no spoon. - flyingmoose

I shouldn't have to say this, but any code, unless otherwise stated, is untested