%hash;
@array = (1212, 1216, 2112, 2111, 33154, 34458, 36339, 154, 556);

for my $nr ( @array ){
    push @{ $hash{length $nr} }, $nr;
}

for my $length ( sort keys %hash ){
    print join(" ", @{ $hash{$length} }),"\n";
}