edit 1: whoops, I see that you wanted numerically next, not the next in the ordered data set. sorry. leave the rest in for historical purposes

edit 2: replace the my @status... line, so it meets your spec, and remove the unneeded sort when foreaching through the values to find each next value

Oh, good. Though there were other good answers between the time I started and when I went to write it up, so far, no one used my idea... Assuming there's only one instance of each data value (*), make a reverse mapping from value back to index

#/usr/bin/perl
#pm1216404

use warnings; use strict;
use 5.010; # for //

#my @status = map {chomp; $_} <DATA>;                # use the chomp t
+o get rid of the newlines from the DATA right away
my @status = sort { $a <=> $b } map {chomp; $_} <DATA>; # edit 2 = sor
+t the status after you read and map it, so now 

my %unmap = map { $status[$_] => $_ } 0..$#status;  # makes a hash of 
+$unmap{value} = index pairs
# use Data::Dumper; print Dumper \@status, \%unmap;
$|++;

foreach my $current ( @status ) {  # edit 2 = remove the sort here, be
+cause it's sorted above
    my $idx = $unmap{$current};
    my $ni = defined $idx ? $idx+1 : undef;
    my $next = defined $ni ? $status[$ni] : undef;
    printf "current=%d, current's index=%s, next idx=%d, next value=%s
+\n", $current, $idx//'<undef>', $ni//'<undef>', $next//'<undef>';
}
__DATA__
11673326
11673329
11673325
11673330
11673321
11673335
[download]

*: if there were more than one instance, I think it would find the next after the _last_ instance