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Number 21: mathematical and symbolic properties | Crazy Numbers

Everything about number 21

Discover a lot of information on the number 21: properties, mathematical operations, how to write it, symbolism, numerology, representations and many other interesting things!


Mathematical properties of 21

Questions and answers
Is 21 a prime number? No
Is 21 a perfect number? No
Number of divisors 4
List of dividers
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1, 3, 7, 21
Sum of divisors 32
Prime factorization 3 x 7
Prime factors
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3, 7

How to write / spell 21 in letters?

In letters, the number 21 is written as: Twenty-one. And in other languages? how does it spell?

21 in other languages
Write 21 in english Twenty-one
Write 21 in french Vingt et un
Write 21 in spanish Veintiuno
Write 21 in portuguese Vinte e um

Decomposition of the number 21

The number 21 is composed of:

1 iteration of the number 2 : The number 2 (two) represents double, association, cooperation, union, complementarity. It is the symbol of duality.... Find out more about the number 2

1 iteration of the number 1 : The number 1 (one) represents the uniqueness, the unique, a starting point, a beginning.... Find out more about the number 1

Mathematical representations and links

Other ways to write 21
In letter Twenty-one
In roman numeral
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XXI
In binary 10101
In octal 25
In hexadecimal 15
In US dollars
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