[eastsider]

By having a wavelength 57 times longer than middle c.

[Izzy Dunne]

By having a wavelength 57 times longer than middle c.

Not quite.
Go down ONE octave, the wavelength is twice middle C.
Go down TWO octaves, the wavelength is four times middle C.
Go down THREE octaves, the wavelength is eight times middle C.
Go down 57 octaves, and the wavelength is 2^57 times middle C.

[Sofa King]

I think he means that a note 57 octaves below a c should be a c, not a b flat.