Chapter 5 - Number Theory and the Real Number System - 5.1 Number Theory: Prime and Composite Numbers - Exercise Set 5.1 - Page 256: 85

241 is not a Germain prime

A prime number $p$ is a Germain prime if $2p+1$ is also a prime. This means that 241 is a Germain prime if: $2(241)+1$ is also a prime number Note that $2(241)+1=483$, which is not a prime number. Thus, 241 is not a Germain prime.