8081
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
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 8082
- 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
- 8080
- Möbius Function
- -1
- Radical
- 8081
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 145
- 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
- 1015
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Largest number not the sum of distinct n-th-order polygonal numbers.at n=29A007419
- Primes p == 1 (mod 8), p = a^2 +64*b^2 such that y^2 = x^3 + p*x has rank 0.at n=39A007765
- Numbers k such that the continued fraction for sqrt(k) has period 59.at n=8A020398
- a(n) = least m such that if r and s in {1/1, 1/2, 1/3, ..., 1/n} satisfy r < s, then r < k/m < (k+4)/m < s for some integer k.at n=41A024846
- Primes formed by concatenating n with n+1.at n=11A030458
- Pair up the numbers.at n=40A030656
- Primes that do not contain any other prime as a proper substring.at n=45A033274
- Number of partitions of n into parts 3k and 3k+1 with at least one part of each type.at n=46A035618
- Number of n-node rooted identity trees of height 6.at n=11A038090
- Denominators of continued fraction convergents to sqrt(126).at n=6A041229
- Denominators of continued fraction convergents to sqrt(504).at n=6A041963
- (s(n)+2)/10, where s(n)=n-th base 10 palindrome that starts with 8.at n=30A043087
- Primes with first digit 8.at n=24A045714
- a(1) = 8; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=39A046258
- Primes whose consecutive digits differ by 7 or 8.at n=10A048419
- Primes whose decimal expansion is a concatenation of two or more consecutive increasing numbers (no leading zeros allowed).at n=12A052087
- Primes p such that x^16 = 2 has no solution mod p, but x^8 = 2 has a solution mod p.at n=14A059287
- Primes p such that x^48 = 2 has no solution mod p, but x^24 = 2 has a solution mod p.at n=10A059669
- Distinct (non-overlapping) twin Harshad numbers whose sum is prime.at n=33A060288
- Primes which are sums of twin Harshad numbers (includes overlaps).at n=38A060290