> In the queryable Wikidata model, there is a property wikibase:sitelinks whose value is an integer that is the number of Wikipedia sites that the item appears on if it is on at least one site.  
> This is what I'm after.  I'm not sure that this value is in the RDF dumps and in the smaller truthy dumps, in particular.

As I see the "latest-all.nt.bz2"  contains the "sitelink" info (  downloaded from here https://dumps.wikimedia.org/wikidatawiki/entities/  )

$ bzcat latest-all.nt.bz2 | grep sitelink | head
<https://www.wikidata.org/wiki/Special:EntityData/Q31> <http://wikiba.se/ontology#sitelinks> "345"^^<http://www.w3.org/2001/XMLSchema#integer> .
<https://www.wikidata.org/wiki/Special:EntityData/Q8> <http://wikiba.se/ontology#sitelinks> "149"^^<http://www.w3.org/2001/XMLSchema#integer> .
<https://www.wikidata.org/wiki/Special:EntityData/Q23> <http://wikiba.se/ontology#sitelinks> "235"^^<http://www.w3.org/2001/XMLSchema#integer> .
<https://www.wikidata.org/wiki/Special:EntityData/Q24> <http://wikiba.se/ontology#sitelinks> "26"^^<http://www.w3.org/2001/XMLSchema#integer> .
<https://www.wikidata.org/wiki/Special:EntityData/Q42> <http://wikiba.se/ontology#sitelinks> "116"^^<http://www.w3.org/2001/XMLSchema#integer> .
<https://www.wikidata.org/wiki/Special:EntityData/Q1868> <http://wikiba.se/ontology#sitelinks> "29"^^<http://www.w3.org/2001/XMLSchema#integer> .
<https://www.wikidata.org/wiki/Special:EntityData/Q2013> <http://wikiba.se/ontology#sitelinks> "119"^^<http://www.w3.org/2001/XMLSchema#integer> .
<https://www.wikidata.org/wiki/Special:EntityData/Q45> <http://wikiba.se/ontology#sitelinks> "338"^^<http://www.w3.org/2001/XMLSchema#integer> .
<https://www.wikidata.org/wiki/Special:EntityData/Q51> <http://wikiba.se/ontology#sitelinks> "292"^^<http://www.w3.org/2001/XMLSchema#integer> .
<https://www.wikidata.org/wiki/Special:EntityData/Q58> <http://wikiba.se/ontology#sitelinks> "138"^^<http://www.w3.org/2001/XMLSchema#integer> .

>  the number of Wikipedia sites 

For example the first line in my example:  Q31 = Belgium ( country in western Europe )   https://www.wikidata.org/wiki/Q31
<https://www.wikidata.org/wiki/Special:EntityData/Q31> <http://wikiba.se/ontology#sitelinks> "345"^^<http://www.w3.org/2001/XMLSchema#integer> .

Q31.Sitelinks= 345 
  ==  [  Wikipedia(278 entries)  + Wikibooks(3 entries) + Wikinews(30 entries)   + Wikiquote(12 entries) + Wikivoyage(21 entries) +  Multilingual sites(1 entry) ]

It is not entirely clear to me that you need the "278" or the "345" as a result.


Kind regards, 
 Imre