The “e” is the public exponent, in openssl genrsa, you can use the option -F4 or -3 to choose between 65537 and 3.
For information on public exponent, you may take a look on this question: https://security.stackexchange.com/questions/2335/should-rsa-public-exponent-be-only-in-3-5-17-257-or-65537-due-to-security-c