7871
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
- 4
- Divisor Sum
- 8352
- Proper Divisor Sum (Aliquot Sum)
- 481
- 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
- 7392
- Möbius Function
- 1
- Radical
- 7871
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 83
- 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
- a(n) = floor( n*(n-1)*(n-2)*(n-3)/27 ).at n=23A011937
- Numbers whose base-4 representation contains exactly two 2's and four 3's.at n=20A045147
- Number of irreducible nonpositively curved triangulations of an n-gon: All internal vertices have at valence at least 6 and no diagonals of the n-gon are allowed.at n=12A060050
- a(n) = sum of modular offsets: mod[n+c,b]-(mod[n,b]+c) for c<=b<=n.at n=41A066809
- Partial sums of A035282.at n=45A078472
- Perfect Abs. Real part of complex z such that Abs[(Total[Divisors[z]]-z)]=Abs[z].at n=26A101367
- Odd numbers n for which 13 is the smallest i (>= 1) with Jacobi symbol J(i,n) getting either a value 0 or -1.at n=25A112076
- Numbers of length n binary words with fewer than 6 0-digits between any pair of consecutive 1-digits.at n=13A145114
- Triangle read by rows: T(n,k) is the number of fixed-point-free involutions of {1,2,...,2n} having k descents (n>=1; 1<=k<2n-1).at n=52A161127
- Least odd number k such that x' = k has n solutions, where x' is the arithmetic derivative (A003415) of x.at n=19A189560
- Triangle of coefficients of polynomials v(n,x) jointly generated with A209999; see the Formula section.at n=49A210287
- Minimum value unattainable as the sum of 7 attained values of i^2 with i in 0..n.at n=35A225280
- Number of ordered triples (i,j,k) with |i|, |j|, |k|, |i*j*k| <= n.at n=23A226359
- Number of partitions p of n such that (number of distinct parts of p) <= max(p) - min(p).at n=32A239955
- Number of n-digit primes whose sum of digits is 7.at n=24A259144
- Exceptional odd numbers D that do not admit a solution to the Pell equation X^2 - D Y^2 = +2.at n=36A263010
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 501", based on the 5-celled von Neumann neighborhood.at n=21A272566
- Numbers whose derivative is equal to the arithmetic derivative.at n=25A273993
- a(n) = Sum_{k=1..n} k * tau(k)^2, where tau is A000005.at n=27A320896
- Positions of first appearances in A124771 = number of distinct contiguous subsequences of compositions in standard order.at n=44A335279