16520
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 32
- Divisor Sum
- 43200
- Proper Divisor Sum (Aliquot Sum)
- 26680
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5568
- Möbius Function
- 0
- Radical
- 4130
- Omega Function (Ω)
- 6
- 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
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 128
- 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
- yes
- Odd
- no
Appears in sequences
- E.g.f.: exp(arcsinh(x)+tan(x)) = 1 + 2*x + 4/2!*x^2 + 9/3!*x^3 + 24/4!*x^4 + 97/5!*x^5 + ....at n=8A013091
- cosh(arcsinh(x)+tan(x))=1+4/2!*x^2+24/4!*x^4+534/6!*x^6+16520/8!*x^8...at n=4A013100
- Numbers k such that sigma(k) = sigma(k+10).at n=23A015880
- Denominators of continued fraction convergents to sqrt(111).at n=11A041201
- Denominators of continued fraction convergents to sqrt(999).at n=11A042935
- Numbers k > 1 such that, in base 8, k and k^2 contain the same digits in the same proportion.at n=15A061662
- Sum of the first n primes whose indices are primes.at n=39A083186
- Number of collinear point 6-tuples in an n X n .. X n 4-dimensional cubical grid.at n=6A178271
- Number of collinear point 6-tuples in a 7 X 7 X 7 X... n-dimensional cubic grid.at n=4A178297
- Number of distinct solutions of sum{i=1..2}(x(2i-1)*x(2i)) = 0 (mod n), with x() in 0..n-1.at n=43A180794
- Number of groups of order prime(n)^6.at n=18A232106
- Number of (n+1) X (6+1) 0..3 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 4 (constant-stress 1 X 1 tilings).at n=10A235287
- Number of 3Xn 0..3 arrays with no element equal to zero plus the sum of elements to its left or zero plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest or one plus the sum of the elements antidiagonally to its northeast, modulo 4.at n=9A240048
- Number of "squares" (repeated identical blocks) in the n-th Fibonacci word.at n=17A248425
- E.g.f.: Series_Reversion( 6*x - 5*x*exp(x) ).at n=3A259066
- Expansion of Product_{k>=0} ((1+x^(3*k+1))/(1-x^(3*k+1)))^2.at n=25A261649
- a(n) = 3*p^2+39*p+344+24*gcd(p-1,3)+11*gcd(p-1,4)+2*gcd(p-1,5), where p = prime(n).at n=18A269749
- Numbers k such that A090086(k), the smallest pseudoprime to base k (not necessarily exceeding k), is a Carmichael number.at n=21A293203
- Triangle read by rows: T(n,k) is the number of labeled quasi-loop-threshold graphs on vertex set [n] with k components, for n >= 1 and 1 <= k <= n.at n=25A350746
- Number of integer partitions of n whose distinct parts have integer mean.at n=44A360241