8641
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 8642
- Proper Divisor Sum (Aliquot Sum)
- 1
- 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
- 8640
- Möbius Function
- -1
- Radical
- 8641
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- 171
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 1076
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Narayana's cows sequence: a(0) = a(1) = a(2) = 1; thereafter a(n) = a(n-1) + a(n-3).at n=25A000930
- Primes that remain prime through 3 iterations of function f(x) = 2x + 9.at n=21A023276
- n written in fractional base 10/8.at n=31A024663
- Primes of the form k^2 - 8.at n=21A028886
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 48 ones.at n=27A031816
- Number of partitions satisfying (cn(0,5) = 0 and cn(2,5) = cn(3,5)).at n=49A036815
- Sizes of successive balls in D_4 lattice.at n=29A046949
- Primes resulting from procedure described in A048393.at n=28A048394
- Primes whose consecutive digits differ by 2 or 3.at n=43A048414
- Pisot sequence P(4,6).at n=20A048625
- Pisot sequence P(6,9).at n=19A048626
- Primes with distinct digits in descending order.at n=41A052014
- First member of a prime triple in a p^2 + p - 1 progression.at n=37A057324
- Prime lucky numbers k (from A031157) such that nextprime(k)=nextlucky(k).at n=14A057698
- Primes with 17 as smallest positive primitive root.at n=13A061329
- Primes p such that the greatest prime divisor of p-1 is 5.at n=30A061599
- Start of the first run of exactly n consecutive primes, none of which are twin primes.at n=21A065044
- Primes which can be expressed as concatenation of cubes.at n=20A066592
- Number of ways to tile a 2 X n room with 1 X 2 Tatami mats. At most 3 Tatami mats may meet at a point.at n=24A068921
- a(n) is the unique odd positive solution x of 2^n = 7x^2+y^2.at n=28A077020