To check the NetSuite Account Number of the account that you're currently logged in, follow the steps provided:
1. Navigate to Support Tab > Click Visit the Suite Answer Site
2. Click the Contact Support by Phone button.
Note: The account number then will pop-up together with the contact details to call NetSuite Support, this would also include your support type.
Release Preview environments and Sandbox environments have the words Release Preview and Sandbox near the company logo on the top portion of their page.
If you are using the legacy Sandbox, the URL will system.sandbox.netsuite.com.