use strict; use warnings;
my $input = '1234562234563334564444565555566789';
my @sets_of_six;
while (length $input > 6){
   my $front = substr($input, 0, 6);
   $input    = substr($input, 6);
   push @sets_of_six, $front;
}

push @sets_of_six, $input if length $input > 0;
use Data::Dumper;
print Dumper( @sets_of_six );