2FA or MFA?

The voices in my head are arguing. Is the following authentication 2FA or MFA?

2-step authentication, 1st step
Username
Password

Success on step 1 invokes step 2, challenge for an OTP (HOTP, TOTP, SMS, etc...).

The voices are arguing over classification of the username. Is it considered 'something I am' or 'something I know'?

Edit: Edited for grammar and spelling.

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