A Sophie Germain prime is a type of prime number. If a prime number is still prime after being multiplied by 2 and adding 1 to the answer, then the original prime is a Sophie Germain prime. A mathematical definition is: a prime number, denoted by "p", is a Sophie Germain prime if "2p+1" is also a prime number. "2p+1" is called a safe prime if it is a prime number.