~nR prints arg in radix n.
The modifier flags and any remaining parameters are used as for
the ~D directive.
~D is the same as ~10R.  
The full form is 
~radix,mincol,padchar,commachar,comma-intervalR.
If no prefix parameters are given to ~R, then a different
interpretation is given.  The argument should be an integer.
For example, if arg is 4:
~R prints arg as a cardinal English number: four.
~:R prints arg as an ordinal English number: fourth.
~@R prints arg as a Roman numeral: IV.
~:@R prints arg as an old Roman numeral: IIII.
For example:
 (format nil "~,,' ,4:B" 13) ⇒  "1101"
 (format nil "~,,' ,4:B" 17) ⇒  "1 0001"
 (format nil "~19,0,' ,4:B" 3333) ⇒  "0000 1101 0000 0101"
 (format nil "~3,,,' ,2:R" 17) ⇒  "1 22"
 (format nil "~,,'|,2:D" #xFFFF) ⇒   "6|55|35"
If and only if the first parameter, n, is supplied,
~R binds
     *print-escape* to false,
     *print-radix* to false, 
     *print-base* to n,
and *print-readably* to false.
If and only if no parameters are supplied,
~R binds *print-base* to 10.