Twenty (20) is a positive integer one more than 19 and one less than 21.

## PropertiesEdit

20 is an abundant, composite number. Its factorization is 2^2*5. The previous abundant number is 18 and the next is 24.

20, being twice the number base of 10, has sometimes been used as a base for naming numbers.

20 is the fourth tetrahedral number (between 10 and 35).

20 is equal to 10!!!!!!!!, the octuple factorial of 10.

## In googology Edit

In Greek-based number-naming systems, 20 is associated with prefix "**icosa-**", and with prefix "**viginti-**" in Latin systems.

20 is the base of a googologism by Sbiis Saibian called menger sponge. It is equal to 20^3###^^^###3 in Extended Cascading-E Notation.

Wiki user Denis Maksudov calls this number **unalum**, and it's equal to f_{1}(10) using the fast-growing hierarchy.^{[1]}

Sbiis Saibian calls the number **dekaxis**, and it's equal to 10+10 using the addition

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