15680
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 42
- Divisor Sum
- 43434
- Proper Divisor Sum (Aliquot Sum)
- 27754
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5376
- Möbius Function
- 0
- Radical
- 70
- Omega Function (Ω)
- 9
- Little Omega Function (ω)
- 3
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
- no
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 27
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- yes
- Odd
- no
Appears in sequences
- Number of partitions into one kind of 1's, two kinds of 2's, and three kinds of 3's.at n=39A002597
- Pisot sequence P(2,9).at n=6A021001
- a(n) is least k such that k and 2k are anagrams in base n (written in base 10).at n=12A023094
- Number of reversible strings with n-1 beads of 2 colors. 4 beads are black. String is not palindromic.at n=26A032091
- Triangle read by rows: T(n,k) = number of labeled digraphs with n nodes and k arcs and without directed paths of length >=2, with 0 <= k <= floor(n^2/4).at n=38A052296
- Numbers k that can be expressed as k = w + x = y*z with w*x = y^3 + z^3 where w, x, y, and z are all positive integers.at n=29A057372
- Numbers k such that Omega(k) = Omega(k+1) + Omega(k+2) + Omega(k+3) + Omega(k+4) where Omega(k) denotes the number of prime factors of k, counting multiplicity.at n=15A078094
- T(n, k) = Stirling1(n+1, k) - Stirling1(n, k-1), for 1 <= k <= n. Triangle read by rows.at n=32A094485
- Integers that are Rhonda numbers to more than one base.at n=29A100988
- a(n) = 4*a(n-1) + 2*a(n-2) for n>1, with a(0)=2, a(1)=9.at n=6A107979
- Triangle read by rows: T(n,k) is the number of Schroeder paths of length 2n and having k weak ascents (1<=k<=n). A Schroeder path of length 2n is a lattice path from (0,0) to (2n,0) consisting of U=(1,1), D=(1,-1) and H=(2,0) steps and never going below the x-axis. A weak ascent in a Schroeder path is a maximal sequence of consecutive U and H steps.at n=31A114655
- Irregular triangle T(n,k) = A098546(n,k) * A036040(n,k), read by rows, 1 <= k <= A000041(n).at n=52A122454
- Irregular triangle T(n,k) = A098546(n,k) * A036040(n,k), read by rows, 1 <= k <= A000041(n).at n=54A122454
- a(n) = the denominator of b(n): {b(n)} is such that the continued fraction (of rational terms) [b(1);b(2),...,b(n)] equals the n-th prime, for every positive integer n.at n=34A128271
- Twice 12-gonal numbers: a(n) = 2*n*(5*n-4).at n=40A152965
- Number of spanning trees in G X P_n, where G = {{1, 2}, {1, 3}, {1, 4}, {1, 5}, {2, 3}, {2, 4}, {2, 5}}.at n=1A167060
- Numbers with 42 divisors.at n=12A175750
- Triangle T(n, k) = coefficients of (n+1)!*(binomial(x+n+1, n+1) - binomial(x, n+1)), read by rows.at n=32A178126
- Numbers of the form p^6*q^2*r where p, q, and r are distinct primes.at n=11A179703
- Upper s-Wythoff sequence, where s=A081276 (eighth cubes). Complement of A184431.at n=48A184432