21905 (number)
21,905 (twentyone thousand nine hundred five) is an odd fivedigits composite number following 21904 and preceding 21906. In scientific notation, it is written as 2.1905 × 10^{4}. The sum of its digits is 17. It has a total of 3 prime factors and 8 positive divisors. There are 16,128 positive integers (up to 21905) that are relatively prime to 21905.
Basic properties
 Is Prime? No
 Number parity Odd
 Number length 5
 Sum of Digits 17
 Digital Root 8
Name
Short name  21 thousand 905 

Full name  twentyone thousand nine hundred five 
Notation
Scientific notation  2.1905 × 10^{4} 

Engineering notation  21.905 × 10^{3} 
Prime Factorization of 21905
Prime Factorization 5 × 13 × 337
Composite numberω(n)  Distinct Factors  3  Total number of distinct prime factors 

Ω(n)  Total Factors  3  Total number of prime factors 
rad(n)  Radical  21905  Product of the distinct prime numbers 
λ(n)  Liouville Lambda  1  Returns the parity of Ω(n), such that λ(n) = (1)^{Ω(n)} 
μ(n)  Mobius Mu  1  Returns:

Λ(n)  Mangoldt function  0  Returns log(p) if n is a power p^{k} of any prime p (for any k >= 1), else returns 0 
The prime factorization of 21,905 is 5 × 13 × 337. Since it has a total of 3 prime factors, 21,905 is a composite number.
Divisors of 21905
8 divisors
τ(n)  Total Divisors  8  Total number of the positive divisors of n 

σ(n)  Sum of Divisors  28392  Sum of all the positive divisors of n 
s(n)  Aliquot Sum  6487  Sum of the proper positive divisors of n 
A(n)  Arithmetic Mean  3549  Returns the sum of divisors (σ(n)) divided by the total number of divisors (τ(n)) 
G(n)  Geometric Mean  148.00337833982  Returns the nth root of the product of n divisors 
H(n)  Harmonic Mean  6.1721611721612  Returns the total number of divisors (τ(n)) divided by the sum of the reciprocal of each divisors 
The number 21,905 can be divided by 8 positive divisors (out of which 0 are even, and 8 are odd). The sum of these divisors (counting 21,905) is 28,392, the average is 3,549.
Other Arithmetic Functions (n = 21905)
φ(n)  Euler Totient  16128  Total number of positive integers not greater than n that are coprime to n 

λ(n)  Carmichael Lambda  336  Smallest positive number such that a^{λ(n)} ≡ 1 (mod n) for all a coprime to n 
π(n)  Prime Pi  ≈ 2456  Total number of primes less than or equal to n 
r_{2}(n)  Sum of 2 squares  32  The number of ways n can be represented as the sum of 2 squares 
There are 16,128 positive integers (less than 21,905) that are coprime with 21,905. And there are approximately 2,456 prime numbers less than or equal to 21,905.
Divisibility of 21905
m  2  3  4  5  6  7  8  9 

n mod m  1  2  1  0  5  2  1  8 
The number 21,905 is divisible by 5.
Classification of 21905
By Arithmetic functions
 Arithmetic
 Deficient
Expressible via specific sums
 Polite
By Powers
 Square Free
Other numbers
 LucasCarmichael
 Sphenic
Base conversion (21905)
Base  System  Value 

2  Binary  101010110010001 
3  Ternary  1010001022 
4  Quaternary  11112101 
5  Quinary  1200110 
6  Senary  245225 
8  Octal  52621 
10  Decimal  21905 
12  Duodecimal  10815 
16  Hexadecimal  5591 
20  Vigesimal  2ef5 
36  Base36  gwh 
Basic calculations (n = 21905)
Multiplication
n×yn×2  43810 

n×3  65715 
n×4  87620 
n×5  109525 
Division
n÷yn÷2  10952.500 

n÷3  7301.666 
n÷4  5476.250 
n÷5  4381.000 
Exponentiation
n^{y}n^{2}  479829025 

n^{3}  10510654792625 
n^{4}  230235893232450625 
n^{5}  5043317241256830940625 
Nth Root
^{y}√n^{2}√n  148.00337833982 

^{3}√n  27.980002728386 
^{4}√n  12.165663908715 
^{5}√n  7.3808886161009 
21905 as geometric shapes
Circle
Radius = nDiameter  43810 

Circumference  137633.17415377 
Area  1507427339.9192 
Sphere
Radius = nVolume  44026927841239 

Surface area  6029709359.6766 
Circumference  137633.17415377 
Square
Length = nPerimeter  87620 

Area  479829025 
Diagonal  30978.348083783 
Cube
Length = nSurface area  2878974150 

Volume  10510654792625 
Space diagonal  37940.572939796 
Equilateral Triangle
Length = nPerimeter  65715 

Area  207772062.56156 
Altitude  18970.286469898 
Triangular Pyramid
Length = nSurface area  831088250.24624 

Volume  1238692546429.3 
Height  17885.357605222 
Cryptographic Hash Functions
md5  6e315707bfe8c9809f10e7336a2455a2 

sha1  631f9c3d9475b092fc06580c1d1558a60861373f 
sha256  213c0e9e7dc1ab0174d62b2c91923cbcdab940bc1019e4b36a8bb21b7611b46c 
sha512  c2d95f847cb82a5b966778a96c4344a88b801e90e12de45f78fa02e7172bdbac53f276e7e29019db71b7d18bd6efe1d2969aade3059f35713957684678037241 
ripemd160  7cc39e89d44b58efbdb78675aa7a240e27aa1fea 