16215
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 27648
- Proper Divisor Sum (Aliquot Sum)
- 11433
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8096
- Möbius Function
- 1
- Radical
- 16215
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 4
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
- yes
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 66
- 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
- a(n) = 1^2 + 3^2 + 5^2 + 7^2 + ... + (2*n-1)^2 = n*(4*n^2 - 1)/3.at n=23A000447
- Binomial coefficient C(47,n).at n=3A010963
- a(n) = binomial coefficient C(n,44).at n=3A010997
- Odd tetrahedral numbers: a(n) = (4*n+1)*(4*n+2)*(4*n+3)/6.at n=11A015219
- Denominator of |Bernoulli(2n+2)| - |Bernoulli(2n)|.at n=22A029765
- a(n) = (prime(n)-3)*(prime(n)-5)*(prime(n)-7)/48.at n=23A030003
- Numbers whose base-4 representation contains exactly three 1's and four 3's.at n=31A045128
- Number of nonempty subsets of {1,2,...,n} in which exactly 4/5 of the elements are <= (n-1)/3.at n=32A048013
- Number of nonempty subsets of {1,2,...,n} in which exactly 4/5 of the elements are <= (n-2)/3.at n=32A048024
- Number of nonempty subsets of {1,2,...,n} in which exactly 4/5 of the elements are <= (n-3)/3.at n=32A048035
- Numbers n such that |phi(n+1)-phi(n)| = |d(n+1)-d(n)|, where phi is Euler's totient function and d(n) = number of divisors of n.at n=8A066219
- a(n) = lcm(n, n+1, n+2)/6.at n=44A067046
- Squarefree tetrahedral numbers.at n=15A070755
- Odd composite numbers k such that cototient(k) - phi(k) = k - 2*phi(k) is an odd prime.at n=7A083255
- Minimum over all permutations b of 1..n of sum b(i)*b^{-1}(i).at n=44A118375
- Number of partitions of n having exactly one part with multiplicity 3.at n=42A118808
- Primitive elements of A119432.at n=35A119433
- Triangle, read by rows, where T(n,k) = C( C(n+2,3) - C(k+2,3) + 1, n-k) for n>=k>=0.at n=24A126450
- a(n) = binomial(prime(n+2), 3).at n=13A126995
- Numbers k such that k and k^2 use only the digits 1, 2, 5, 6 and 9.at n=23A137006