16420
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 34524
- Proper Divisor Sum (Aliquot Sum)
- 18104
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6560
- Möbius Function
- 0
- Radical
- 8210
- 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
- 159
- 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
- a(n) = a(n-2) + 2*a(n-3) + a(n-4).at n=19A036605
- a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 4, where m = 2^(p+1) + 2 - n and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1, a(2) = 2, and a(3) = 4.at n=15A049913
- For a number k of length L, let f(k) be the sum of the products of the first i digits of k multiplied by the last L-i digits, for i from 1 to L-1, e.g., f(1234) = 1*234 + 12*34 + 123*4 = 1134. Sequence gives k such that f(k) = k.at n=8A065759
- Let f(x)=(largest digit of x)^(smallest digit of x) + x (A097385). Sequence gives numbers n such that f(n) and f(n+1) are both prime.at n=38A097387
- Sum of sixth powers of first n Fibonacci numbers.at n=5A098532
- Negative numbers written in a bits-of-Pi/primorial base system.at n=9A109839
- Indices n such that A134204(n) < n.at n=21A133242
- Number of n X 6 0..1 arrays with rows unimodal and antidiagonals nondecreasing.at n=4A224407
- T(n,k)=Number of nXk 0..1 arrays with rows unimodal and antidiagonals nondecreasing.at n=49A224409
- Number of 5Xn 0..1 arrays with rows unimodal and antidiagonals nondecreasing.at n=5A224412
- Numbers of the form 4^j + 6^k, for j and k >= 0.at n=44A226813
- Sum of numbers in the n-th antidiagonal of the reciprocity array of 0.at n=40A259574
- Consider any concatenation of the type n = concat(a,b). Sequence lists numbers that are the sum of the products of some of such couples a and b.at n=26A265737
- Number of ways to split a strict integer partition of n into consecutive subsequences with strictly decreasing sums.at n=42A318684
- a(n) = Sum_{k=1..floor(sqrt(n))} 2^floor(n/k-k).at n=15A360303