10821
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 14432
- Proper Divisor Sum (Aliquot Sum)
- 3611
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7212
- Möbius Function
- 1
- Radical
- 10821
- Omega Function (Ω)
- 2
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 42
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- Squarefree Number
- yes
- 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 the continued fraction for sqrt(k) has period 78.at n=34A020417
- Number of partitions of n into parts not of form 4k+2, 24k, 24k+11 or 24k-11. Also number of partitions in which no odd part is repeated, with at most 5 parts of size less than or equal to 2 and where differences between parts at distance 5 are greater than 1 when the smallest part is odd and greater than 2 when the smallest part is even.at n=47A036034
- Convolution of natural numbers n >= 1 with Fibonacci numbers F(k), for k >= 5.at n=12A037140
- Erroneous version of A028419.at n=15A046664
- Discriminants of real quadratic fields with class number 1 and related continued fraction period length of 22.at n=35A051963
- Expansion of series related to Liouville's Last Theorem: g.f. sum_{t>0} (-1)^(t+1) *x^(t*(t+1)/2) / ( (1-x^t)^5 *product_{i=1..t} (1-x^i) ).at n=15A059822
- Symmetric square table of coefficients, read by antidiagonals, where T(n,k) is the coefficient of x^n*y^k in f(x,y) that satisfies f(x,y) = (1-xy)/[(1-x)(1-y)] + xy*f(x,y)^3.at n=60A086626
- Main diagonal of square table A086626 of coefficients of x^n*y^k in f(x,y) that satisfies f(x,y) = (1-xy)/[(1-x)(1-y)] + xy*f(x,y)^3.at n=5A086627
- Number of partitions of n such that the numbers of prime and composite parts differ by at least 1.at n=43A116450
- G.f.: exp( Sum_{n>=1} x^n/n * Product_{d|n} (1 + d*x^n)^d ).at n=21A205482
- Numbers that match polynomials over {0,1} that have a factor containing 3 as a coefficient; see Comments.at n=29A208181
- Numbers that match polynomials over {0,1} that have a factor containing -3 as a coefficient; see Comments.at n=9A208182
- Magic constants of the magic cubes 3 X 3 X 3 composed of prime numbers.at n=19A239671
- Expansion of e.g.f.: exp(Sum_{k>=1} k^2 * x^k).at n=5A255807
- Row sums of the Bell transform of the complementary Bell numbers (A264435).at n=10A265022
- a(n) = Sum_{k=0..n}((binomial(2*k,k)/(k+1)*binomial(2*n+2,n-k))).at n=6A270530
- Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 785", based on the 5-celled von Neumann neighborhood.at n=6A273558
- Square array A(n,k), n >= 0, k >= 1, read by antidiagonals, where column k is the expansion of e.g.f. exp(Sum_{j=1..k} j^2*x^j).at n=50A293724
- Square array A(n,k), n >= 0, k >= 1, read by antidiagonals, where column k is the expansion of e.g.f. exp(Sum_{j=1..k} j^2*x^j).at n=60A293724
- Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f. exp(Sum_{j>=1} j^(k-1)*x^j).at n=41A293785