If you want to extend it to UTF-8 characters:

$ perl -CA -le 'print ord shift' 😈
128520

$ perl -CS -le 'print chr shift' 128520
😈

With bash, ksh or zsh builtins:

$ printf "\U$(printf %08x 128520)\n"
😈

If you want to extend it to UTF-8 characters (assuming you're in a UTF-8 locale):

$ perl -CA -le 'print ord shift' 😈
128520

$ perl -CS -le 'print chr shift' 128520
😈

With bash, ksh or zsh builtins:

$ printf "\U$(printf %08x 128520)\n"
😈

If you want to extend it to UTF-8 characters:

$ perl -CA -le 'print ord shift' 😈
128520

$ perl -CS -le 'print chr shift' 128520
😈

If you want to extend it to UTF-8 characters:

$ perl -CA -le 'print ord shift' 😈
128520

$ perl -CS -le 'print chr shift' 128520
😈

With bash, ksh or zsh builtins:

$ printf "\U$(printf %08x 128520)\n"
😈