9840
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 40
- Divisor Sum
- 31248
- Proper Divisor Sum (Aliquot Sum)
- 21408
- 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
- 2560
- Möbius Function
- 0
- Radical
- 1230
- Omega Function (Ω)
- 7
- Little Omega Function (ω)
- 4
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
- 73
- Smith Number
- yes
- 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
- MacMahon's generalized sum of divisors function.at n=39A002127
- a(n) = n*(n+4)*(n+5)/6.at n=36A005586
- Theta series of D_5 lattice.at n=37A005930
- a(n) = floor(n*(n-1)*(n-2)/7).at n=42A011889
- Pisot sequences L(3,7) or S(3,7).at n=9A020730
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (Fibonacci numbers), t = (odd natural numbers).at n=22A024463
- Expansion of 1/((1-x)(1-8x)(1-9x)(1-12x)).at n=3A024778
- a(n) = (3^n - 3)/2.at n=8A029858
- Least term in period of continued fraction for sqrt(n) is 5.at n=33A031429
- Numbers whose base-3 representation contains exactly one 0 and no 2's.at n=36A044994
- 12 times triangular numbers.at n=40A049598
- Coefficient triangle of polynomials (rising powers) related to Pell number convolutions. Companion triangle is A058402.at n=6A058403
- Coefficient triangle of polynomials (falling powers) related to Pell number convolutions. Companion triangle is A058404.at n=9A058405
- Numbers k such that sigma (x) = k has exactly 11 solutions.at n=11A060678
- Array read by antidiagonals: T(k,d) = number of different hyperplanes in d-space with integer coefficients in set {-k,...,-1,0,1,...,k}.at n=35A061559
- Barriers for bigomega(n): numbers n such that, for all m < n, m + bigomega(m) <= n.at n=44A068597
- Pair the natural numbers such that the n-th pair is (k, k+p(n)) where k is the smallest number not occurring earlier and p(n) is the n-th prime. (1, 3), (2, 5), (4, 9), (6, 13), (7, 18), (8, 21), (10, 27), (11, 30), (12, 35), (14, 43), ... This is the sequence of the product of the members of every pair.at n=36A075316
- Sums of members of groups in A076063.at n=26A076066
- a(n) = 3*(a(n-2) + 1), with a(0) = 1, a(1) = 3.at n=15A087503
- Number of primes of the form 30k + 23 less than 10^n.at n=5A091171