Short Answer 
Ex-presidents of the United States receive lifelong protection from the Secret Service, which varies based on the assessed threat level. The precise number of agents assigned is classified to maintain security and protect privacy.
Step 1: Lifelong Protection Eligibility
An ex-president of the United States is entitled to receive lifelong protection from the United States Secret Service. This protection ensures their safety and security even after they have left office, acknowledging the ongoing potential threats they may face due to their former position.
Step 2: Variable Agent Assignment
The number of Secret Service agents assigned to an ex-president is not fixed and depends on several factors. These factors include the current threat level against the ex-president and other situational considerations that may arise. This means that some ex-presidents may have more agents assigned to them than others, based on their unique circumstances.
Step 3: Classified Information
It is crucial to understand that the exact number of agents assigned to an ex-president’s protection detail is classified information. This policy is in place to maintain effective security measures and protect the privacy of the individuals involved, ensuring that potential threats are managed without disclosing sensitive details publicly.