7840
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 36
- Divisor Sum
- 21546
- Proper Divisor Sum (Aliquot Sum)
- 13706
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 2688
- Möbius Function
- 0
- Radical
- 70
- Omega Function (Ω)
- 8
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 26
- 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
- Expansion of k/(4*q^(1/2)) in powers of q, where k defined by sqrt(k) = theta_2(0, q)/theta_3(0, q).at n=10A001938
- 4-dimensional figurate numbers: a(n) = n*binomial(n+2, 3).at n=13A002417
- Expansion of (1-x)^(-3) * (1-x^2)^(-2).at n=26A002624
- Numbers that are the sum of 3 positive 5th powers.at n=36A003348
- Triangle read by rows: the Bell transform of the triple factorial numbers A008544 without column 0.at n=24A004747
- 2^(2n-6) * C(n,3) - 2^(n-2) * C(n,4).at n=4A008465
- Specific heat coefficients for square lattice spin 5/2 Ising model.at n=18A010114
- a(n) = floor(n*(n-1)*(n-2)/15).at n=50A011897
- Theta series of 6-dimensional lattice of det 8.at n=39A029543
- Shortest edge c of (measured by the longest edge) primitive Euler bricks (a, b, c, sqrt(a^2 + b^2), sqrt(b^2 + c^2), sqrt(a^2 + c^2) are integers).at n=19A031175
- a(n) = 10*n^2.at n=28A033583
- Number of nonnegative solutions of x1^2 + x2^2 + ... + x8^2 = n.at n=31A045850
- 12-gonal (or dodecagonal) numbers: a(n) = n*(5*n-4).at n=40A051624
- Numbers k that can be expressed as k = w + x = y*z with w*x = y^3 + z^3 where w, x, y, and z are all positive integers.at n=24A057372
- a(n) = 2^(n-3)*n^2*(n+3).at n=7A058645
- Triangle T(n,m) of number of labeled n-node T_0-hypergraphs with m distinct hyperedges (empty hyperedge included), m=0,1,...,2^n.at n=25A059084
- Numbers k such that sigma(x) = k has exactly 6 solutions.at n=36A060662
- Intrinsic 9-palindromes: n is an intrinsic k-palindrome if it is a k-digit palindrome in some base.at n=31A060879
- Least m such that n = m mod tau(m) if such m exists, otherwise 0.at n=27A066708
- Seventh column of triangle A067425.at n=3A067427