9157
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 9158
- 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
- 9156
- Möbius Function
- -1
- Radical
- 9157
- 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
- 109
- 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
- 1135
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Bosonic string states.at n=35A005308
- Eleven iterations of Reverse and Add are needed to reach a palindrome.at n=33A015992
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 54 ones.at n=23A031822
- Primes with first digit 9.at n=32A045715
- Numbers n such that n and n+4^k are all primes for k=1,2,3.at n=22A049493
- a(n) and a(n)+4^k are primes at least for k=1,2,3,4.at n=10A049494
- a(n) and a(n)+4^k are primes at least for k=1,2,3,4,5.at n=3A049495
- Surround numbers of a length 2n zig-zag.at n=26A060641
- Numbers p from A001125 such that 2*p-3 is prime.at n=15A063939
- Numbers which need eleven 'Reverse and Add' steps to reach a palindrome.at n=31A065216
- Sum of the first n safe primes.at n=24A066869
- a(n+1) = a(n)+greatest prime divisor of a(n-1).at n=43A078695
- a(n) = smallest prime > n*prime(n).at n=45A079779
- Let the sequence s_n be defined by s_n(1) = n+1 and for k > 1, s_n(k) = k*s_n(k-1)+1. Then a(n) is the first prime in the sequence s_n.at n=10A084755
- Smallest prime x > n such that x (mod n) = x (mod prime(n)).at n=45A091313
- Numbers n such that n!! - 2 is prime.at n=17A094144
- a(n) is the smallest number greater than a(n-1) such that in a(0) through a(n) no digit occurs more than once more than any other digit.at n=32A095204
- Greatest prime that differs from prime(n) in decimal representation by exactly one editing operation: deletion, insertion, or substitution.at n=36A097722
- Expansion of psi(x^2) / f(-x) in powers of x where psi(), f() are Ramanujan theta functions.at n=29A098613
- Expansion of 1/(1-x^2*c(2*x)), c(x) the g.f. of A000108.at n=8A108308