Retrieve list of site collections from Office 365 Tenenat

Hi

I have a requirement to create a list of all available Site collections in the given O365 tenancy. The purpose of this is to know what are the new site collections created and asisgn a owner for each site collection etc.

I found through client object model it is not possible to access Site collection level details. Is my understanding correct? Is it possible through REST API ? Please help.

Thanks in advance

Kiran