6439
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 6624
- Proper Divisor Sum (Aliquot Sum)
- 185
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6256
- Möbius Function
- 1
- Radical
- 6439
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- 168
- Smith Number
- yes
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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) = floor(n*phi^12), where phi is the golden ratio, A001622.at n=20A004927
- Numbers k such that the continued fraction for sqrt(k) has period 64.at n=33A020403
- a(n) = diagonal sum of right justified array T given by A027082.at n=10A027101
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 79.at n=20A031577
- Triangle of D-analogs of Stirling numbers of first kind.at n=23A039762
- Triangle of D-analogs of Stirling numbers of first kind, rows reversed.at n=25A039763
- Number of partitions satisfying cn(1,5) + cn(4,5) <= 1.at n=44A039856
- a(n) = least odd number which can be represented in the form p + 2*k^2, k>0, in n different ways.at n=40A060004
- Composite n such that sigma(n)-phi(n) divides sigma(n)+phi(n).at n=45A061367
- Dimension of the space of weight n cuspidal newforms for Gamma_1( 100 ).at n=40A063373
- Smallest semiprime p*q such that q >= p and q mod p = n.at n=43A064910
- Nonprime numbers n such that q=phi(n)/(sigma(n)-n-1) is an integer and n is not a prime square.at n=38A070161
- Vertical of triangular spiral in A051682.at n=37A081271
- First column of array in A081998.at n=45A082000
- Least x = a(n) such that sum of common prime divisors (without multiplicity) of sigma(x) and phi(x) equals n, or 0 if such number (apparently) does not exist.at n=24A082056
- Least x=a(n) such that product of common prime-divisors [without multiplicity] of sigma(x) and phi(x) equals n; or 0 if n is not a squarefree number or if no such x exists. Among indices n only squarefree numbers arise because multiplicity of prime factors is ignored.at n=45A082057
- Counterexamples to the conjecture that an even, prime-indexed triangular plus 1 equals a prime or that an odd, prime-indexed triangular minus 2 equals a prime.at n=8A097785
- Numbers k such that A109631(k) + A109631(k+1) = A109631(k+2).at n=7A109651
- Semiprimes n such that 3*n + 4 is a square.at n=18A112666
- Smallest number m such that A114228(m) = n.at n=32A114229