Sec1836[42 U.S.C. 1395o]  Every individual who—

(1) is entitled to hospital insurance benefits under part A, or

(2) has attained age 65 and is a resident of the United States, and is either (A) a citizen or (B) an alien lawfully admitted for permanent residence who has resided in the United States continuously during the 5 years immediately preceding the month in which he applies for enrollment under this part,

is eligible to enroll in the insurance program established by this part.