6872
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 23
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 12900
- Proper Divisor Sum (Aliquot Sum)
- 6028
- 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
- 3432
- Möbius Function
- 0
- Radical
- 1718
- Omega Function (Ω)
- 4
- 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
- 150
- 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
- Representation degeneracies for Ramond strings.at n=14A005306
- a(n) = Sum_{k=0..n} T(k) where T(n) are the tribonacci numbers A000073.at n=15A008937
- Define the generalized Pisot sequence T(a(0),a(1)) by: a(n+2) is the greatest integer such that a(n+2)/a(n+1) < a(n+1)/a(n). This is T(4,8).at n=12A018921
- Numbers k such that Fib(k) == 21 (mod k).at n=43A023179
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 19.at n=42A031517
- a(1)=1, a(2)=2, a(3)=3; for n >= 3, a(n) is smallest number such that all a(i) for 1 <= i <= n are distinct, all a(i)+a(j) for 1 <= i < j <= n are distinct and all a(i)+a(j)+a(k) for 1 <= i < j < k <= n are distinct.at n=20A036241
- Number of primes between n*100000 and (n+1)*100000.at n=20A038825
- Numbers whose base-5 representation contains exactly two 2's and three 4's.at n=23A045288
- a(n) = Sum_{k=1..n} binomial(k, n mod k).at n=18A072951
- Duplicate of A008937.at n=15A073769
- Sum of GCD's of parts in all partitions of n.at n=30A078392
- Triangle read by rows: T(n,k) is the number of binary sequences of length n containing k subsequences 0011 (n,k>=0).at n=32A118884
- a(1) = 1. a(n) = sum of the earlier terms of the sequence, a(k), where GCD(n,a(k)) is <= k, for 1 <= k <= n-1.at n=17A119990
- Numbers k such that 6*p(k)*p(k+1)*p(k+2)*p(k+3)*p(k+4)-1 and 6*p(k)*p(k+1)*p(k+2)*p(k+3)*p(k+4)+1 are twin primes with p(h) = h-th prime.at n=20A129310
- List of different composites in Pascal-like triangles with index of asymmetry y = 2 and index of obliquity z = 0 or z = 1.at n=29A141066
- INVERTi transform of A006973.at n=6A156791
- Triangle read by rows, T(n,k) = (A156791(n-k+1) * (A006973 * 0^(n-k))).at n=21A156792
- Triangle read by rows, T(n,k) = (A156791(n-k+1) * (A006973 * 0^(n-k))).at n=29A156792
- Total number of balls in room in variant of the tennis ball problem (cf. A171074).at n=4A171076
- Triangulations of the disk, G_{1,n}.at n=8A210696