I think it has to do with the font your using. not all character numbers are the same in each font. to find the correct number use the following
(ascii "°")
mine its 176 so then use that number with (chr
(setq nbrg2 (strcat (itoa intd) (chr 176) mint "'" sec (chr 34)))
This will display all your character numbers of the current font.
https://www.cadtutor.net/forum/topic/75383-text-ascii/?do=findComment&comment=596047