7715
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 9264
- Proper Divisor Sum (Aliquot Sum)
- 1549
- 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
- 6168
- Möbius Function
- 1
- Radical
- 7715
- 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
- 52
- 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
- Prefix (or Levenshtein) codes for natural numbers.at n=35A010097
- Sum of digits in n-th term of A006711.at n=29A022480
- a(n) = (n + 2)*(2*n^2 - n + 3)/6.at n=28A056520
- Centered 19-gonal numbers.at n=28A069132
- A Wallis pair (x,y) satisfies sigma(x^2) = sigma(y^2); sequence gives y's for indecomposable Wallis pairs with x < y (ordered by values of x).at n=20A075769
- Indices n of primes p(n), p(n+2) such that p(n)+1 and p(n+2)+1 have the same largest prime factor.at n=11A105404
- Numerator of 1/n^3 + 2/(n-1)^3 + 3/(n-2)^3 +...+ (n-1)/2^3 + n.at n=3A120287
- Numbers k such that k and k^2 use only the digits 1, 2, 5, 7 and 9.at n=13A137009
- Smallest k such that 41^k mod k = n.at n=46A178202
- Number of Dyck n-paths all of whose ascents and descents have prime lengths.at n=18A210735
- a(n) = 9*n^2 - 13*n + 5.at n=29A214675
- Fixed points of permutations A249990 and A252448.at n=12A252458
- G.f. A(x) satisfies: x = Sum_{n>=1} x^n * A(-n*x)^n.at n=5A266812
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 315", based on the 5-celled von Neumann neighborhood.at n=22A271248
- Number of heptagons that can be formed with perimeter n.at n=43A288253
- a(n) = a(n-1) + 3*a(n-2) -2*a(n-3) - 2*a(n-4), where a(0) = -1, a(1) = -1, a(2) = 2, a(3) = 1.at n=16A295852
- Take a squarefree semiprime and take the difference of its prime factors. If it is a squarefree semiprime repeat the process. Sequence lists the squarefree semiprimes that generate other squarefree semiprimes only in the first k steps of this process. Case k = 4.at n=13A296811
- Indices i where a run of nonzero values starts in A305671.at n=21A305672
- Indices i such that A305671(i) != A305671(i-1).at n=41A305674
- Least k such that Sum_{m=1..k} 1/m > Product_{i=1..n} 1/(1 - 1/prime(i)).at n=43A328684