7518
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
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 17280
- Proper Divisor Sum (Aliquot Sum)
- 9762
- 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
- 2136
- Möbius Function
- 1
- Radical
- 7518
- Omega Function (Ω)
- 4
- 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
- yes
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 88
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- yes
- Odd
- no
Appears in sequences
- Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite BRE = Brewsterite (Sr,Ba)2[Al4Si12O32].10H2O starting with a T4 atom.at n=12A019085
- a(n) = a(n-1) + a(n-2) + 1 for n>1, a(0)=0, a(1)=1.at n=16A022311
- a(n) = T(n,n-3), T given by A026536. Also number of integer strings s(0), ..., s(n), counted by T, such that s(n) = 3.at n=10A026540
- [ exp(2/5)*n! ].at n=6A030972
- Every run of digits of n in base 5 has length 2.at n=38A033003
- Numbers n such that A048767(n+1)=A048767(n).at n=12A048769
- Numbers k such that 2^k + 15 is prime.at n=40A057197
- a(n) = (sum of digits of n)^4 - (sum of digits^4 of n).at n=37A069964
- 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=32A075316
- Sum of the quadratic residues of prime(n).at n=40A076409
- Average of 4 primes where the integer Schwarzian derivative is zero.at n=8A094903
- Numbers n such that r3(k) * 2^n + 1 is prime, where r3() = A002277 and k is the number of decimal digits of 2^n.at n=22A095967
- See formula line.at n=3A101004
- a(n) consecutive digits descending beginning with the digit 4 give a prime.at n=5A120829
- Let M be the matrix defined in A111490. Sequence gives M(2,1)-M(1,2), M(2,1)+M(3,1)+M(3,2)-M(1,2)-M(1,3)-M(2,3), etc.at n=40A123329
- An eighth of the product of three integers surrounding the (n+1)-st prime, minus half of the product of the 3 numbers surrounding n+1.at n=11A141535
- Number of walks within N^2 (the first quadrant of Z^2) starting and ending at (0,0) and consisting of n steps taken from {(-1, -1), (-1, 0), (0, -1), (0, 1), (1, 0), (1, 1)}.at n=8A151372
- n times the n-th noncomposite.at n=41A164931
- Triangle T(n,k) read by rows: T(n, k) = (m*n - m*k + 1)*T(n - 1, k - 1) + (5*k - 4)*(m*k - (m - 1))*T(n - 1, k) where m = 0.at n=42A166973
- T(n,k) = Number of n-step self-avoiding walks on a k X k X k cube summed over all starting positions.at n=38A187162