8156
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 6
- Divisor Sum
- 14280
- Proper Divisor Sum (Aliquot Sum)
- 6124
- 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
- 4076
- Möbius Function
- 0
- Radical
- 4078
- Omega Function (Ω)
- 3
- 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
- 65
- 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
- Numbers k such that the continued fraction for sqrt(k) has period 96.at n=13A020435
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 44 ones.at n=30A031812
- a(n) = a(n-1) + a(m) for n >= 4, where m = 2*n - 2 - 2^(p+1) and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = a(2) = a(3) = 1.at n=31A050027
- Heights of peaks of more than 8000 meters (as of Sep 25 2001), in decreasing order.at n=7A064296
- Sums of (one or more distinct) k-perfect numbers.at n=33A083865
- n times n+2 gives the concatenation of two numbers m and m-5.at n=1A116252
- a(n) = 2^(n+1) - 3*n.at n=11A123203
- Numbers k such that the sum of the first k primes is prime and the sum of the squares of the first k primes is also prime.at n=38A124225
- a(n) = A129152(n) / 5^5, where A129152 is the trajectory of 5^6 under A003415, the arithmetic derivative.at n=11A129286
- Concatenation of first two digits and last two digits of n-th even perfect number.at n=36A138875
- Sums of distinct perfect numbers.at n=10A185351
- Monotonic ordering of nonnegative differences 2^i-6^j, for 40>=i>=0, j>=0.at n=40A192116
- Arises in enumerating Huffman codes, compact trees, and sums of unit fractions.at n=15A194632
- Number of 0..n arrays x(0..6) of 7 elements with zero 4th differences.at n=26A200274
- Number of 2 X 2 matrices having all elements in {-n,...n} and determinant 2.at n=23A209984
- Number of tilings of a 3 X n rectangle using straight (3 X 1) trominoes and 2 X 2 tiles.at n=20A219968
- Number of 6 X 6 0..n matrices with each 2 X 2 subblock idempotent.at n=28A224668
- G.f.: Sum_{n>=0} x^n / (1-3*x)^(2*n+1) * [Sum_{k=0..n} C(n,k)^2 * x^k] * [Sum_{k=0..n} C(n,k)^2 * 3^k * x^k].at n=5A246813
- Numbers n such that the arithmetic derivative of the totient(n) is equal to the cototient(n).at n=45A272528
- Number of compositions (ordered partitions) of n into decimal palindromes (A002113).at n=14A282584