Yotta-

Yotta is the largest unit prefix in the metric system, denoting a factor of 1024 or 1  000  000  000  000  000  000  000  000. It has the unit symbol Y. The prefix name is derived from the Greek οκτώ (októ), meaning eight, because it is equal to 10008. It was added to the SI in 1991.

Usage examples:
 * The mass of the Earth is 5972.6 Yg.
 * The mass of the oceans is about 1.4 Yg.
 * The total power output of the Sun is approximately 385 YW.
 * The observable universe is estimated to be 880 Ym in diameter.
 * One yottabyte is a unit of digital information that contains one septillion bytes. The yobibyte (YiB) is a related unit that uses a binary prefix, and means 10248 bytes, which is approximately 1.2 septillion bytes.