9857
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 29
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 9858
- 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
- 9856
- Möbius Function
- -1
- Radical
- 9857
- 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
- 60
- 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
- 1216
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Base-9 Armstrong or narcissistic numbers (written in base 10).at n=17A010353
- Numbers k such that the continued fraction for sqrt(k) has period 73.at n=6A020412
- Primes or negative values of primes in the sequence b(n) = 47*n^2 - 1701*n + 10181, n >= 0.at n=36A050267
- Smallest value of x such that M(x) = -n, where M(x) is Mertens's function A002321.at n=41A051401
- Inverse Mertens function: smallest k such that |M(k)| = n, where M(x) is Mertens's function A002321.at n=41A051402
- An inverse to Mertens's function: smallest k >= 2 such that Mertens's function |M(k)| (see A002321) is equal to n.at n=42A060434
- Numbers k such that prime(k) + prime(k+1) is a square.at n=28A064397
- Numbers n such that p(n) + p(n+1) is a square and n is prime.at n=5A064398
- Group the natural numbers such that the n-th group contains n terms and the group sum is the smallest possible prime: (2), (1, 4), (3, 5, 9), (6, 7, 8, 10), (11, 12, 13, 14, 17), (15, 16, 18, 19, 20, 21), ... Sequence gives group sums.at n=26A075345
- a(n) = the n-th prime with sum of decimal digits = n, or 0 if no such number exists.at n=28A075361
- Primes associated with groups in A076077.at n=24A076076
- a(n) = smallest k such that the digit sum of 7k is n.at n=39A077494
- Octo numbers (a polygonal sequence): a(n) = 5*n^2 - 6*n + 2 = (n-1)^2 + (2*n-1)^2.at n=44A079273
- Primes p such that (3*p)^2 + p^2 + 3^2 and (3*p)^2 - p^2 - 3^2 are both prime.at n=25A079796
- Proth primes: primes of the form k*2^m + 1 with odd k < 2^m, m >= 1.at n=35A080076
- Duplicate of A075361.at n=28A082258
- Lessers of twin prime pairs whose greater has a prime prime index.at n=36A094068
- Balanced primes of order five.at n=26A096697
- Lower bound b of twin primes pairs such that b's digital reverse is also prime.at n=44A101781
- Lower bound twin primes such that their digital reverse is prime and a lower bound twin prime.at n=14A101783