$ perl -E 'use Unicode::UCD "charinfo"; my @cps = qw{U+DFA8 0xDFA8 0x1C9140 0xE6BAAA 0xFFFFFFFFFFFFFFFF}; for (@cps) { say "$_: ", defined charinfo($_) ? "Assigned" : "Unassigned" }'
U+DFA8: Assigned
0xDFA8: Assigned
0x1C9140: Unassigned
0xE6BAAA: Unassigned
Hexadecimal number > 0xffffffff non-portable at /Users/ken/perl5/perlbrew/perls/perl-5.28.0t/lib/5.28.0/Unicode/UCD.pm line 355.
0xFFFFFFFFFFFFFFFF: Unassigned

##</code><code>##

$ perl -E 'use Unicode::UCD "charinfo"; my @cps = qw{U+DFA8 0xDFA8 0x1C9140 0xE6BAAA 0xFFFFFFFFFFFFFFFF}; for (@cps) { say "$_: ", defined charinfo($_) ? "Assigned" : "Unassigned" }'
U+DFA8: Assigned
0xDFA8: Assigned
0x1C9140: Unassigned
0xE6BAAA: Unassigned
Hexadecimal number > 0xffffffff non-portable at /Users/ken/perl5/perlbrew/perls/perl-5.26.0t/lib/5.26.0/Unicode/UCD.pm line 365.
0xFFFFFFFFFFFFFFFF: Unassigned