8571
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 11432
- Proper Divisor Sum (Aliquot Sum)
- 2861
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5712
- Möbius Function
- 1
- Radical
- 8571
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- no
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- no
- Lucas Number
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 171
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- Squarefree Number
- yes
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 29.at n=41A031527
- Numbers k such that the decimal encoding of the prime factorization of k (A067599) ends in k.at n=1A067254
- a(1) = 5; a(n) is smallest number > a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=47A074340
- Numerator of 3 * H(n,3,1), a generalized harmonic number. See A075135.at n=4A074596
- a(n) is equal to the number of positive integers m less than or equal to 10^n such that m is not divisible by at least one of the primes 2,5 and is not divisible by at least one of the primes 3,7.at n=2A128957
- Composite numbers, not ending with 0, sharing a 3-digit sequence with some of its prime factors.at n=1A131523
- Concatenation of first two digits and last two digits of n-th Mersenne prime A000668(n).at n=26A138863
- G.f.: A(q) = exp( Sum_{n>=1} A002129(n) * 3*A038500(n) * q^n/n ).at n=18A161804
- A trisection of A161804: a(n) = A161804(3n) for n>=0.at n=6A161805
- a(n) = 1 - 2*n^2 + 4*n*(1 + 2*n^2)/3.at n=15A168547
- a(n) = (4*n^3 - 6*n^2 + 8*n + 9 + 3*(-1)^n)/12.at n=30A168582
- G.f. A(x) satisfies A(x) = x + A(A(x)^3) where A(x) = Sum_{n>=1} a(n)*x^(2*n-1).at n=7A179486
- G.f.: exp( Sum_{n>=1} A181411(n)*x^n/n ) where A181411(n) = Sum_{k=0..n} C(n,k)*sigma(n+k).at n=7A181410
- G.f. satisfies: A(x) = 1 + x*A(x)^3 + x*(A(x) - 1)^3.at n=7A192132
- Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal or diagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..2 n X 2 array.at n=17A220147
- a(n) = Sum_{k=1, n} phi(k)*index(k, n), with phi(k) the Euler totient A000010(k) and index(k,n) the position of 1/k in the n-th row of the Farey sequence of order k, A049805(n,k).at n=37A244396
- a(n) = number of polynomials a_k*x^k + ... + a_1*x + a_0 with k > 0, integer coefficients, only distinct integer roots, and a_0 = p^n (p is a prime).at n=16A248348
- p-INVERT of the upper Wythoff sequence (A001950), where p(S) = 1 - S.at n=6A289974
- Numbers k such that 2*10^(2k) + 2*10^k + 1 are prime.at n=10A296444
- Number of nX5 0..1 arrays with every element equal to 2, 3, 5, 7 or 8 king-move adjacent elements, with upper left element zero.at n=8A298927