Hello ovedpo15,

You can use the module List::Util::min and do something like that:

#!/usr/bin/env perl
use strict;
use warnings;
use List::Util 'min';

my @arr = ( 11673326,
        11673329,
        11673325,
        11673330,
        11673321,
        11673335 );

print "Please insert a number:\n";
chomp(my $number = <>);
my $next_largest = min grep $_ > $number, @arr;

if(defined($next_largest)) {
    print $next_largest."\n";
}
else {
    print "undef\n";
}

__END__

$ perl test.pl
Please insert a number:
11673326
11673329
$ perl test.pl
Please insert a number:
11673321
11673325
$ perl test.pl
Please insert a number:
11673335
undef
[download]

Hope this helps, BR