Because of irregularities in definition and usage of the kilobyte, the exact number could be any one of the following:
A yottabyte is 1024 times a zettabyte.
To clarify the meaning(1) above, the International Electrotechnical Commission (IEC), a standards body, in 1998 defined new prefixes by combining the International System of Units (SI) prefixes with the word "binary" (see Binary prefix). They did not provide a name for this number, although, it would probably be zebibyte. This naming convention has not, as of 2003, been widely adopted.