The registration number for your company can be found on the company's Certificate of Formation/Incorporation (Articles of Incorporation).
You can view/download your certificate from the DOCUMENT section of your dashboard here:
This will be the "File Number" on your Certificate stamp from the registered agent. You can find this number at the bottom left corner of the page. Please check the example below:
For Wyoming: This will be the "Original ID" on the top-right corner of the certificate. Please check the example below:
You can check the registration numbers for each state as follows: