15861
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 22464
- Proper Divisor Sum (Aliquot Sum)
- 6603
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9920
- Möbius Function
- -1
- Radical
- 15861
- Omega Function (Ω)
- 3
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 102
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- Strong pseudoprimes to base 52.at n=14A020278
- Numbers whose base-4 representation contains exactly three 1's and four 3's.at n=30A045128
- Terms in A112039 that are divisible by 3, divided by 3.at n=26A112040
- Numbers k such that 9^k - 2 is a prime.at n=14A128455
- Expansion of Product_{k > 0} (1 + f(k)*x^k), where f(k) = A147952(A004001(k)).at n=37A147982
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (-1, 0, 1), (0, 1, -1), (1, 0, 0)}.at n=11A148079
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (0, 1, -1), (0, 1, 0), (1, 0, 0), (1, 0, 1)}.at n=7A151076
- Triangle T(n, k) = (-1)^(n-k)*StirlingS1(n, k) + (-1)^k*StirlingS1(n, n-k) + (-1)^n*StirlingS1(n, k)*StirlingS1(n, n-k), read by rows.at n=29A155744
- Triangle T(n, k) = (-1)^(n-k)*StirlingS1(n, k) + (-1)^k*StirlingS1(n, n-k) + (-1)^n*StirlingS1(n, k)*StirlingS1(n, n-k), read by rows.at n=34A155744
- a(n) = A057641(A094348(n)).at n=28A181852
- Floor-Sqrt transform of large central Delannoy numbers (A001850).at n=12A192674
- Strings of 5 digits from 1...9, such that no formula using the single digits in the given order exists that evaluates to 0.at n=37A288355
- Number of n X n 0..1 arrays with every element equal to 0, 2, 3, 4 or 6 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.at n=4A300960
- Number of nX5 0..1 arrays with every element equal to 0, 2, 3, 4 or 6 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.at n=4A300963
- T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 2, 3, 4 or 6 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.at n=40A300966
- Numbers k such that k and k+1 have the same denominator of the harmonic means of their divisors.at n=9A348415
- Numbers k such that k and k+1 have the same denominator of the harmonic means of their unitary divisors.at n=7A348657