21

Properties by base:

Base 1021 (2 digits)
Digit Sum: 3
Digital Root: 3 sad
Base 20b10101 (5 digits)
Digit Sum: 0b11
Digital Root: 0b1 always happy
Base 8025 (2 digits)
Digit Sum: 07
Digital Root: 07 sad
Base 160x15 (2 digits)
Digit Sum: 0x6
Digital Root: 0x6 sad

More about this number at Positiv Integers and Number Empire.

The number is not a prime.

Its 2 (2 unique) factors are:
3
7

Its 4 divisors are:
1
3
7
21
Its aliquote sum is:
11
makeing it a deficient number.

In HTML this number represents this color:  
#000015
 

In the work of Johann Sebastian Bach BWV 21 is Ich hatte viel Bekümmernis [Weimarer Fassung in c]

The number appears at position 93 of the decimal digits of π surrounded by
286208998628034825342117067982148086513282 Source: The Pi-Search Page

Computations done with Math::BigInt 1.999811 and Math::Pari 2.030523 based on PARI/GP 2.11.3 (elapsed: 865.756ms; cpu: 81.1179999999999ms)


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