7811
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 7992
- Proper Divisor Sum (Aliquot Sum)
- 181
- 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
- 7632
- Möbius Function
- 1
- Radical
- 7811
- 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
- 101
- 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
- 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 87.at n=23A031585
- Concatenate prevprime(n), n, and nextprime(n).at n=5A049857
- Frobenius number of the numerical semigroup generated by consecutive cubes.at n=2A069763
- A089450 indexed by A000040.at n=4A089525
- Number of (ordered) sequences of coins (each of which has value 1, 5, 10, 25, 50 or 100) which add to n.at n=32A114044
- A129957(n) - n*(n-1)/2.at n=20A129959
- a(n) = (5^n - 3)/2.at n=6A137410
- Ulam's spiral (WSW spoke).at n=22A143854
- Integers of the form 4n+3 for which Sum_{i=1..u} J(i,4n+3) obtains value zero exactly 7 times, when u ranges from 1 to (4n+3). Here J(i,k) is the Jacobi symbol.at n=7A166057
- Squarefree semiprimes k such that (m+1)^2-k is also a square, where m = ceiling(sqrt(k)).at n=38A180656
- Floor(1/{(9+n^4)^(1/4)}), where {} = fractional part.at n=25A184633
- Positions in A218787 and A218788 of successive distinct values.at n=41A218611
- Square number array read by ascending antidiagonals: T(1,k) = 2*k + 1, and T(n,k) = (2*n^(k+1)-n-1)/(n-1) otherwise.at n=60A238339
- Semiprimes which are the arithmetic mean of three consecutive primes.at n=29A242218
- Non-palindromic balanced numbers in base 16.at n=41A256080
- Expansion of 1/(1-x-x^2-x^3-x^5+x^8-x^9).at n=15A257792
- Semiprimes whose prime factors are of equal binary length and which differ from each other in exactly two bit positions.at n=24A261074
- Coordination sequence for (3,3,5) tiling of hyperbolic plane.at n=19A265072
- Sum of divisors of the products of the smaller and larger parts of the partitions of n into two parts.at n=35A270528
- In the binary race of Pi, where the race leader changes.at n=43A278920