Is it possible to gain a pagerank for a site without building any content ?

Suppose if i'll or get a backlink from a PR6 website will i get PR4 for my content less site ?

Yes, it is possible to gain a pagerank without content (I think there are at least some short writings on the page), but getting PR 4 with just one PR 6 link seems me impossible. Even if you have content it is hard to get PR 4 with just one PR 6 link.

Yep there are many domains which do not have any content only parked and gain the PR.

Some people started to build links before putting content even ... so this can be also one reason.

Hello,

I got a page rank 1 for one page with title, descripton and keywords. No links to the page.

This is quite possible but in this case you will be able to gain PR 1 or 2 or 3 only. Beyond 3 there is least chances to gain.

Reason is either you have very good domain name or there sister website linked to that one or there was content earlier but now that content removed.