7856
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 26
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 10
- Divisor Sum
- 15252
- Proper Divisor Sum (Aliquot Sum)
- 7396
- 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
- 3920
- Möbius Function
- 0
- Radical
- 982
- Omega Function (Ω)
- 5
- 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
- 145
- 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 k divides the (left) concatenation of all numbers <= k written in base 9 (most significant digit on right and removing all least significant zeros before concatenation).at n=7A029526
- a(0)=2; a(n) is the smallest k > a(n-1) such that the fractional part of k^(1/11) starts with n.at n=26A034076
- Lesser of two consecutive numbers each divisible by a fourth power.at n=15A068782
- Floor(average of first n Fibonacci numbers).at n=24A078620
- Triangle read by rows: T(n,k) is number of paths from (0,0) to (3n,0) that stay in the first quadrant (but may touch the horizontal axis), consisting of steps u=(2,1),U=(1,2), or d=(1,-1) and have k pyramids of the first kind (a pyramid of the first kind is a sequence u^pd^p for some positive integer p, starting at the x-axis).at n=22A108451
- Numbers k such that k + sigma(k) + phi(k) is a triangular number.at n=39A115906
- a(n) = 9^n+6^n-1^n.at n=4A155647
- Number of ways that a tile in the form of a strip of n congruent regular hexagons stuck together on successive parallel edges can be surrounded by one layer of copies of itself in a plane. Ways that differ by rotation or reflection are not counted as different. The surrounded tile is the exact surrounded region.at n=4A159295
- Number of arrangements of 4 nonzero numbers x(i) in -n..n with the sum of x(i)*x(i+1) equal to zero.at n=19A188250
- Triangle of coefficients of polynomials u(n,x) jointly generated with A208932; see the Formula section.at n=41A208931
- Numbers k such that k and k + 1 are both of the form p*q^4 where p and q are distinct primes.at n=1A215197
- 6^n mod 10000.at n=20A216128
- Numbers equal to the Euler totient function of their arithmetic derivative: k = phi(k').at n=37A217715
- G.f.: 1 / (1 + 12*x*G(x)^4 - 16*x*G^5) where G(x) = 1 + x*G(x)^6 is the g.f. of A002295.at n=4A226705
- a(n) is the number of base-4 n-digit numbers requiring only binary digits in bases 3 and 4.at n=47A230360
- 8-step Fibonacci sequence starting with 0,0,0,0,1,0,0,0.at n=21A251741
- a(n) = 5*2^n + 3^n + 15.at n=8A254368
- Numbers n such that T(n) + T(n+1) + ... + T(n+22) is a square, where T = A000217 (triangular numbers).at n=3A257707
- Numbers k such that [r[s*k]] - [s[r*k]] = -2, where r = sqrt(2), s=sqrt(3), and [ ] = floor.at n=37A259584
- Number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 401", based on the 5-celled von Neumann neighborhood.at n=45A271803