17909
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 26
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 17910
- 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
- 17908
- Möbius Function
- -1
- Radical
- 17909
- 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
- 92
- 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
- 2052
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Numbers k such that 135*2^k+1 is prime.at n=47A032417
- Start of a string of exactly 2 consecutive (but disjoint) pairs of twin primes.at n=37A035790
- Near twin primes of order 12: twin primes p,p+2 such that p+12 and p+14 are primes.at n=42A079292
- Numbers n such that n*359# +-1 are twin primes, where 359# = 72nd primorial (A002110(72)).at n=19A087907
- a(n) = (1/n!)*A001688(n).at n=10A094793
- Number of doubletons in all partitions of n. By a doubleton in a partition we mean an occurrence of a part exactly twice (the partition [4,(3,3),2,2,2,(1,1)] has two doubletons, shown between parentheses).at n=37A116646
- Triangle read by rows. Let g(n) = n if n is a prime, otherwise g(n) = 1. Let p(0) = 1, p(n) = g(n)*p(n-1). Row n gives coefficients of Product_{j=0..n} (x - p(j)), with row 0 = {1}.at n=38A118686
- Numbers k such that (14^k - 5^k)/9 is prime.at n=5A128350
- Positions at which the sum of the digits of e up to that point equals the sum of the digits of Pi up to that point.at n=23A131660
- Prime numbers p such that p^3 - (p+1)^2 and p^3 + (p+1)^2 are both primes.at n=19A137476
- Primes congruent to 48 mod 53.at n=39A142578
- Primes congruent to 32 mod 59.at n=33A142759
- Primes congruent to 36 mod 61.at n=32A142834
- a(n) = 484*n + 1.at n=36A158326
- The smaller member of a twin prime pair in which both primes are emirps.at n=34A175215
- a(n) = (n+9)*a(n-1) + (n-1)*a(n-2), a(-1)=0, a(0)=1.at n=4A176736
- Primes of the form 13*n^2+3*n+1.at n=17A176783
- Position where 10^n-1 occurs in the Kaprekar sequence A006886.at n=36A193992
- Numbers k such that A057775(k) is the factor of a Fermat number 2^(2^m) + 1 for some m.at n=48A201364
- Number of partitions p of n such that max(p)-min(p) = 8.at n=41A218571