1815
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 3192
- Proper Divisor Sum (Aliquot Sum)
- 1377
- 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
- 880
- Möbius Function
- 0
- Radical
- 165
- 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
- yes
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 55
- 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
- no
- Odd
- yes
Appears in sequences
- Numbers k such that k / (sum of digits of k) is a square.at n=46A001102
- Generalized sum of divisors function.at n=35A002130
- 4-dimensional figurate numbers: a(n) = (5*n-1)*binomial(n+2,3)/4.at n=9A002418
- Expansion of (1-x)^(-3) * (1-x^2)^(-2).at n=17A002624
- a(n) = n*(n+1)*(n+2)^2/6.at n=9A004320
- Maxima of the rows of the triangle A259095.at n=32A005577
- Coordination sequence T2 for Zeolite Code EMT.at n=35A008087
- a(n) = 2^n - Fibonacci(n+2).at n=11A008466
- Triangle of coefficients in expansion of (1+11x)^n.at n=23A013618
- Bisection of A001400.at n=29A014125
- Numbers k that divide s(k), where s(1)=1, s(j)=15*s(j-1)+j.at n=23A014865
- a(n) = (2*n - 7)*n^2.at n=11A015242
- Numbers n such that phi(n) * sigma(n) + 16 is a perfect square.at n=37A015729
- Number of spanning trees in a Moebius ladder M_n with 2n vertices.at n=5A020871
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (Lucas numbers), t = (primes).at n=13A024478
- Duplicate of A024478.at n=13A025090
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (Lucas numbers), t = (primes).at n=12A025098
- Sums of five consecutive squares: a(n) = n^2 + (n+1)^2 + (n+2)^2 + (n+3)^2 + (n+4)^2.at n=17A027578
- a(n) = n^2 + n + 9.at n=42A027694
- a(n) = (n+1)*binomial(n+1,8).at n=3A027768