Zetta (symbol Z) is a SI prefix in the SI system of units denoting 10²¹ or 1 000 000 000 000 000 000 000.

Adopted in 1991, it comes from the French sept, meaning seven, because it is equal to 1000⁷.

There was a bogus SI prefix of the same value, Hepa, which was informally introduced a few years before the promulgation of Zetta. It apparently came from the Greek ἑπτά, hepta, seven.

See also

• SI prefix
• Binary prefix

External link

• BIPM website