How to sort byCodeUnit.permutations.filter(...)

[Uknown]

I wrote a small program for Project Euler problem 41 ( 
https://projecteuler.net/problem=41 ).

--- project_euler_41.d
void main()
{
	import math_common : primesLessThan;
	import std.stdio : writeln;
	import std.conv : parse;
	import std.algorithm : permutations, canFind, filter, each, sort;
	import std.utf : byCodeUnit;
	import std.range : assumeSorted;
	import std.array : array;

	auto primes = primesLessThan(9_999_999UL).assumeSorted;

	"1234567".byCodeUnit
		.permutations
		.filter!(a => primes.canFind(a.parse!uint))
		.each!(a => a.writeln);
}
---

The problem is this prints a list of numbers. The task requires 
only the largest, so the intuitive fix is to add `.array.sort[$ - 
1].writeln` in place of the `each`, but this prints an array of 
`1234567`s instead of the permutations. Does anyone know how to 
sort the filter result without modifying the individual results?