15717
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
- 3
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 23424
- Proper Divisor Sum (Aliquot Sum)
- 7707
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9360
- Möbius Function
- 0
- Radical
- 1209
- Omega Function (Ω)
- 4
- 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
- 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
- no
- Odd
- yes
Appears in sequences
- Spontaneous magnetization coefficients for square lattice spin 2 Ising model.at n=44A010103
- a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2) and t is A000201 (lower Wythoff sequence).at n=47A023866
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (natural numbers), t = A000201 (lower Wythoff sequence).at n=46A024863
- Numbers k such that 141*2^k+1 is prime.at n=40A032420
- Consider the first run of composites that contains at least two numbers whose largest prime factor is prime(n), n >= 2. a(n) is the second of these numbers.at n=9A137800
- "Trim" numbers that are not prime; see reference for definition.at n=39A145555
- 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, -1, 0), (0, 1, 0), (1, 0, 1), (1, 1, -1)}.at n=8A150015
- Partial sums of A138202.at n=25A164940
- First string of 43 consecutive composite numbers.at n=33A177949
- Number of 0..n arrays x(0..6) of 7 elements with zero 4th differences.at n=31A200274
- Semiperimeters s of primitive Pythagorean triples (a, b, c) where a, b, c and s are not squarefree.at n=31A237620
- Numbers k such that 7*R_k + 20 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=15A256426
- Total sum T(n,k) of the sizes of all blocks with maximal element k in all set partitions of {1,2,...,n}; triangle T(n,k), n>=1, 1<=k<=n, read by rows.at n=40A270701
- Total sum T(n,k) of the sizes of all blocks with minimal element k in all set partitions of {1,2,...,n}; triangle T(n,k), n>=1, 1<=k<=n, read by rows.at n=40A270702
- Total sum of the sizes of all blocks with maximal element n in all set partitions of {1,2,...,2n-1}.at n=4A270703
- Total sum of the sizes of all blocks with maximal element 5 in all set partitions of {1,2,...,n}.at n=4A270759
- Total sum of the sizes of all blocks with minimal element 5 in all set partitions of {1,2,...,n}.at n=4A270768
- Number of 3 X n 0..1 arrays with no element equal to more than two of its horizontal, diagonal or antidiagonal neighbors and with new values introduced in order 0 sequentially upwards.at n=15A281471
- a(n) = Sum(psi(k-1)*psi(n-k-1),k=0..n)+(1-(-1)^n)/2, where psi(k) = A000931(k+6).at n=25A285187
- Numbers n such that A083722(n) > 1 and A083722(n) occurs earlier in A083722.at n=14A293894