The number is on the back of the card ... just like any other CC or Debit card.
For help with your pre-paid Visa card:
Call (888) 285-4169
There is a “Help” link in the top corner of the web site for the card:
https://www.turboprepaidcard.intuit.com/
The Turbo® Visa® Debit Card is provided by Green Dot Corporation and is issued by Green Dot Bank pursuant to a license from Visa U.S.A Inc. Green Dot Corporation is a member service provider for Green Dot Bank, Member FDIC. Visa is a registered trademark of Visa International Service Association. Green Dot Bank operates under the following registered trade names: GoBank, Green Dot Bank and Bonneville Bank. All of these registered trade names are used by, and refer to, a single FDIC-insured bank, Green Dot Bank. Deposits under any of these trade names are deposits with Green Dot Bank and are aggregated for deposit insurance coverage. Green Dot is a registered trademark of Green Dot Corporation.