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Five positive divisors

Source: UMD 2023 I #8

October 27, 2023
UMDnumber theory

Problem Statement

How many positive integers less than 11 million have exactly 55 positive divisors? a. 1b. 5c. 11d. 23e. 24 \mathrm a. ~ 1\qquad \mathrm b.~5\qquad \mathrm c. ~11 \qquad \mathrm d. ~23 \qquad \mathrm e. ~24
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