13691
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 13692
- Proper Divisor Sum (Aliquot Sum)
- 1
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 13690
- Möbius Function
- -1
- Radical
- 13691
- 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
- 151
- 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
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 1618
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Coordination sequence for MgNi2, Position Ni3.at n=29A009934
- a(0) = 1, a(n) = 9*n^2 + 2 for n>0.at n=39A010002
- Primes that remain prime through 3 iterations of function f(x) = 4x + 3.at n=33A023281
- Primes that are palindromic in base 9.at n=30A029977
- Smallest nontrivial extension of n-th square which is a prime.at n=36A030685
- Number of bracelets (turnover necklaces) of n beads of 2 colors, 5 of them black.at n=40A032279
- Initial terms of '4-block' primes as described in A032591.at n=19A032592
- Numerators of continued fraction convergents to sqrt(882).at n=6A042704
- Base-9 palindromes that start with 2.at n=27A043029
- Primes of the form k^2 + 2.at n=14A056899
- Smallest prime that begins with the n-th square in decimal notation.at n=36A065145
- a(n), for n > 1, equals the least prime p such that p - a(n-1) is a cube, a(1)=2.at n=20A076201
- Near twin primes of order 18: twin primes (p, p+2) such that p+18 and p+20 are primes.at n=24A079304
- Duplicate of A056899.at n=14A089921
- Lessers of twin prime pairs whose greater has a prime prime index.at n=40A094068
- Least initial value for a Euclid/Mullin sequence whose 3rd term (= least prime divisor of 1+2p) equals the n-th prime. prime(1)=2 is never a third term, so offset=2.at n=32A094464
- Lesser of twin balanced primes (A090403).at n=8A096694
- Primes of the form m^k+k, with m and k > 1.at n=18A099227
- Primes p = prime(k) such that both p+2 and prime(k+6)-2 are prime numbers.at n=31A105413
- Twin prime pairs k-1 and k+1 such that the squares of both are present in A115557.at n=38A115560