Finding your NetSuite account number
Your NetSuite account number can be found in your browser URL when you are logged in to NetSuite via any browser.
In some cases you may have letters before or after the number, ie tstdrv58861, acct58861, 588861_sb1 (sandbox). In such a case letters and numbers will make up your account number.
In the example below the account number is 588861.
Alternate ways to find your account number
NetSuite has documented alternate methods of finding your account number in their help center here.