15726
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
- 31464
- Proper Divisor Sum (Aliquot Sum)
- 15738
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- yes
Derived Values
- Euler's Totient
- 5240
- Möbius Function
- -1
- Radical
- 15726
- 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
- 84
- 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
- yes
- Odd
- no
Appears in sequences
- Increasing length runs of consecutive composite numbers (endpoints).at n=10A008995
- Number of labeled servers of dimension 18.at n=3A027405
- Decimal part of n-th root of a(n) starts with digit 2.at n=51A034079
- Smallest a(n)>2 such that all integers strictly between a(n)-n and a(n) are composite.at n=42A075741
- Expansion of eta(q^6) * eta(q^10) / (eta(q) * eta(q^15)) in powers of q.at n=39A094023
- Number of connected antisymmetric relations on n unlabeled nodes.at n=5A101460
- Numbers n such that 9*10^n + 2*R_n + 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.at n=9A103094
- Expansion of q * (chi(-q^3) * chi(-q^5)) / (chi(-q) * chi(-q^15))^2 in powers of q where chi() is a Ramanujan theta function.at n=38A123630
- Expansion of q * chi(q^3) * chi(q^5) / (chi(q) * chi(q^15))^2 in powers of q where chi() is a Ramanujan theta function.at n=38A145786
- First string of 43 consecutive composite numbers.at n=42A177949
- Array: row n shows the coefficients of the characteristic polynomial of the n-th principal submatrix of f(i,j)=(L(i) if i=j and 1 otherwise) (A204129).at n=22A204130
- Number of 0..n arrays x(0..3) of 4 elements with each no smaller than the sum of its two previous neighbors modulo (n+1).at n=16A207101
- Where record values occur in A276781, when starting from A276781(2)=1.at n=43A276782
- a(n) is the smallest integer k > n such that (k+1)(k+2)...(2k-2n+1)/(k(k-1)...(k-n+1)) is an integer.at n=42A290791
- Positive integers that have exactly nine representations of the form 1 + p1 * (1 + p2* ... * (1 + p_j)...), where [p1, ..., p_j] is a (possibly empty) list of distinct primes.at n=30A317399
- Number of edges in a complete bipartite graph where the n vertices of each part are placed on the vertices, and on opposite sides, of a regular 2n-gon.at n=14A392973