As a SharePoint Online admin, you can access a list of information about each site collection. This specific information includes a list of site administrators, the number of subsites, storage and usage quotas, and the default URL and title. You can view all of this information in the Site Collection Properties dialog box from the SharePoint admin center.
View properties of a site collection
Sign in to Office 365 as a Global admin or a SharePoint Online admin.
Go to the SharePoint admin center.
On the SharePoint admin center page, select Site Collections.
Select the check box next to the site collection for which you want to view properties.
On the Site Collections tab, in the Manage section, select Properties.
The Site Collection Properties page is displayed.
Description of properties
This table describes the site collection properties you can view in the SharePoint admin center.