Comment 5 for bug 1851437

Pontificating aside, it's unportable to rely on such ill-specified behavior:

--- Clozure
? (typep 3 '(number))
> Error: Invalid type specifier: (NUMBER) .
> While executing: CCL::VALUES-SPECIFIER-TYPE, in process listener(1).

-- ECL
ECL (Embeddable Common-Lisp) 16.1.3 (git:UNKNOWN)
> (typep 3 '(number))
Condition of type: SIMPLE-ERROR
(NUMBER) is not a valid type specifier.

-- CLISP
Welcome to GNU CLISP 2.49.92 (2018-02-18) <http://clisp.org/>
[1]> (typep 3 '(number))
*** - TYPEP: invalid type specification (NUMBER)

-- CMUCL
CMU Common Lisp 20d (20D Unicode), running on dougk.cam.corp.google.com
* (typep 3 '(number))
Error in function LISP::%%TYPEP: Unknown type specifier: (NUMBER)