The SI prefixes above are not the only extreme ones. Others such as xenno (x) (10-27) and xenna (X) (1027), or vendeko (v) (10-33) and vendeka (V) (1033) exist, and can help simplify the expression of extreme numbers.
Table 3.2: Prefixes and symbols of SI units ¶ Prefix; Symbol; Multiplying factor ¶ xenna; X; 1027 ¶ yotta; Y; 1024 ¶ zetta; Z; 1021
2002, Roger Blandford, "To the Lighthouse", in: Marat Gilfanov, Rashid Sunyaev and Eugene Churazov (ed.), Lighthouses of the universe: the most luminous celestial objects and their use for cosmology, Springer Science & Business Media, page 394:
In the limiting case the potential differences along the magnetic field lines approach the impressively large, fundamental "gravitational" value, (Gμ0)1/2c3 ∼ 1XV. (1 xenna eV ≡ 103 yotta eV ≡ 1027eV!)
2015, Claude Phipps, No Wonder You Wonder!: Great Inventions and Scientific Mysteries, Springer, page 14:
The mass of the earth is about 6 Xennagrams, or Xg.
2015, Claude Phipps, No Wonder You Wonder!: Great Inventions and Scientific Mysteries, Springer, page 62:
But that's nothing: our universe is about 0.8 Xm (Xennameters, billions of billions of billions of meters) in diameter.