bytes.
Although the term megabyte is almost universally used
to refer to 
bytes, such usage is deprecated in favor of the standard SI naming convention of
1 megabyte being equal to 
bytes.
Mebibyte
See also
Byte, Exbibyte, Gibibyte, Kibibyte, Megabyte, Pebibyte, TebibyteExplore with Wolfram|Alpha
References
National Institute of Standards. "Prefixes for Binary Multiples." http://physics.nist.gov/cuu/Units/binary.html.Referenced on Wolfram|Alpha
MebibyteCite this as:
Weisstein, Eric W. "Mebibyte." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Mebibyte.html