力ずく問題は苦手なインタプリタ―だが、速度に配慮した書き方をすればこの規模だと数分程度で解ける…

use feature qw{:5.16 signatures say};
$m = 1234567;
%h = map{$_ => ++$k} 2..$m;
for $i (2..int(sqrt $m)) {
　if (exists $h{$i}) {
　　for ($i..(int($m / $i)+1)) { delete $h{$i * $_} }
　}
}
@p = sort{$a <=> $b} keys %h;
%o = map{$p[$_] => $_} 0..$#p;
for $i (0..$#p-2) {
　$p1 = $p[$i];
　last if $m <= 3 * $p1;
　for $j ($i+1..$#p-1) {
　　$p2 = $p[$j]; $s = $p1 + $p2;
　　$r = $m - $s; last if $r <= $p2;
　　$n++ if exists $o{$r};
　}
}
print "n = $n\n";

実行結果 (CPUは Core-i7 8995u、Mem: 32GB)
$ time perl 21_738_prime+1234567.pl
n = 151055501

real 5m48.035s
user 5m44.468s
sys 0m3.250s

出題者の解と合わん…＞＜