EDIT Superscript latin small letter o. Is used for example in French and Spanish for abbrevation of number = Nº.

 jb  :  pilar 

EDIT The Numero has a code point of its own: № U+2116 NUMERO SIGN.
In general, the ordinal indicators ª U+00AA FEMININE ORDINAL INDICATOR and º U+00BA MASCULINE ORDINAL INDICATOR are used in Italian, Portuguese, and Spanish for writing ordinal numbers. Additionally, Spanish uses them for some abbreviations.

 83.236.181.13  jb