17891
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
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 17892
- 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
- 17890
- Möbius Function
- -1
- Radical
- 17891
- 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
- 48
- 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
- 2050
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Quintan primes: p = (x^5 - y^5)/(x - y).at n=10A002649
- Expansion of g.f. 1/((1-2*x)*(1-11*x)).at n=4A016135
- Primes congruent to 14 mod 59.at n=37A142741
- Primes congruent to 18 mod 61.at n=34A142816
- Number of primes p in the range 9 < p <= prime(10^n) that have most significant and least significant decimal digit both equal to 7.at n=5A145711
- 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=23A166057
- Primes p such that (p reversed)+10 is a square.at n=8A167474
- Primes p such that q*p+-Mod(p,q) are primes, for q=7.at n=25A178387
- Potential magic constants of 9 X 9 magic squares composed of consecutive primes.at n=32A191679
- Sum of numbers with no '0' decimal digits whose sum of digits equals n.at n=5A211072
- Number of compositions of n where the difference between largest and smallest parts equals one.at n=20A214259
- Smallest primes a(n) such that 1 + a(1), 1 + a(1) + a(1)*a(2), ..., 1 + a(1) + a(1)*a(2) + ... + a(1)*a(2)*a(3)*...*a(n) are prime numbers with a(1) = 2 and a(i) < a(i+1).at n=40A227613
- Numbers of the form x^4 + y*x^3 + y^2*x^2 + y^3*x + y^4, where x and y are positive integers.at n=44A299505
- a(n) = Sum_{i=1..n} prime(n*(i - 1) + i).at n=17A319012
- Primes p such that (p^128 + 1)/2 is prime.at n=13A341230
- Smallest number k with A355915(k) = n.at n=28A356792
- Total number of parts in all partitions of n with designated summands.at n=17A388064
- Prime numbersat n=2050