21987 (number)
21,987 (twentyone thousand nine hundred eightyseven) is an odd fivedigits composite number following 21986 and preceding 21988. In scientific notation, it is written as 2.1987 × 10^{4}. The sum of its digits is 27. It has a total of 4 prime factors and 12 positive divisors. There are 12,528 positive integers (up to 21987) that are relatively prime to 21987.
Basic properties
 Is Prime? No
 Number parity Odd
 Number length 5
 Sum of Digits 27
 Digital Root 9
Name
Short name  21 thousand 987 

Full name  twentyone thousand nine hundred eightyseven 
Notation
Scientific notation  2.1987 × 10^{4} 

Engineering notation  21.987 × 10^{3} 
Prime Factorization of 21987
Prime Factorization 3^{2} × 7 × 349
Composite numberω(n)  Distinct Factors  3  Total number of distinct prime factors 

Ω(n)  Total Factors  4  Total number of prime factors 
rad(n)  Radical  7329  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  0  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 21,987 is 3^{2} × 7 × 349. Since it has a total of 4 prime factors, 21,987 is a composite number.
Divisors of 21987
12 divisors
τ(n)  Total Divisors  12  Total number of the positive divisors of n 

σ(n)  Sum of Divisors  36400  Sum of all the positive divisors of n 
s(n)  Aliquot Sum  14413  Sum of the proper positive divisors of n 
A(n)  Arithmetic Mean  3033.333  Returns the sum of divisors (σ(n)) divided by the total number of divisors (τ(n)) 
G(n)  Geometric Mean  148.28014027509  Returns the nth root of the product of n divisors 
H(n)  Harmonic Mean  7.2484615384623  Returns the total number of divisors (τ(n)) divided by the sum of the reciprocal of each divisors 
The number 21,987 can be divided by 12 positive divisors (out of which 0 are even, and 12 are odd). The sum of these divisors (counting 21,987) is 36,400, the average is 30,33.,333.
Other Arithmetic Functions (n = 21987)
φ(n)  Euler Totient  12528  Total number of positive integers not greater than n that are coprime to n 

λ(n)  Carmichael Lambda  348  Smallest positive number such that a^{λ(n)} ≡ 1 (mod n) for all a coprime to n 
π(n)  Prime Pi  ≈ 2465  Total number of primes less than or equal to n 
r_{2}(n)  Sum of 2 squares  0  The number of ways n can be represented as the sum of 2 squares 
There are 12,528 positive integers (less than 21,987) that are coprime with 21,987. And there are approximately 2,465 prime numbers less than or equal to 21,987.
Divisibility of 21987
m  2  3  4  5  6  7  8  9 

n mod m  1  0  3  2  3  0  3  0 
The number 21,987 is divisible by 3, 7 and 9.
Classification of 21987
By Arithmetic functions
 Deficient
Expressible via specific sums
 Polite
Base conversion (21987)
Base  System  Value 

2  Binary  101010111100011 
3  Ternary  1010011100 
4  Quaternary  11113203 
5  Quinary  1200422 
6  Senary  245443 
8  Octal  52743 
10  Decimal  21987 
12  Duodecimal  10883 
16  Hexadecimal  55e3 
20  Vigesimal  2ej7 
36  Base36  gyr 
Basic calculations (n = 21987)
Multiplication
n×yn×2  43974 

n×3  65961 
n×4  87948 
n×5  109935 
Division
n÷yn÷2  10993.500 

n÷3  7329.000 
n÷4  5496.750 
n÷5  4397.400 
Exponentiation
n^{y}n^{2}  483428169 

n^{3}  10629135151803 
n^{4}  233702794582692561 
n^{5}  5138423344489661338707 
Nth Root
^{y}√n^{2}√n  148.28014027509 

^{3}√n  28.014873050709 
^{4}√n  12.177033311734 
^{5}√n  7.3864063393252 
21987 as geometric shapes
Circle
Radius = nDiameter  43974 

Circumference  138148.39534896 
Area  1518734384.2688 
Sphere
Radius = nVolume  44523217209223 

Surface area  6074937537.0751 
Circumference  138148.39534896 
Square
Length = nPerimeter  87948 

Area  483428169 
Diagonal  31094.313595897 
Cube
Length = nSurface area  2900569014 

Volume  10629135151803 
Space diagonal  38082.601106017 
Equilateral Triangle
Length = nPerimeter  65961 

Area  209330537.6295 
Altitude  19041.300553008 
Triangular Pyramid
Length = nSurface area  837322150.51799 

Volume  1252655590664.7 
Height  17952.310324858 
Cryptographic Hash Functions
md5  22e915482d7829dd65af3d7a7aaaca82 

sha1  7e440a7904ab16b4bd078ae524b8d1b086e51a06 
sha256  b4a9151f18a5525da013d3ecdcf231872e2a1a0ff3b29ade4c42ff8584796a46 
sha512  4b1c858532e4254dda55f9062cd5877fafae5ee9b119a45e987f79daa5c585956c41c024acb32b7e2f47ab9850ca5ee436acc356d4f680fe96874c385de88a16 
ripemd160  d4c33da390dafa6ffbf47d22f8ea4a173de1fb02 