15857
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
- 4
- Divisor Sum
- 16116
- Proper Divisor Sum (Aliquot Sum)
- 259
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 15600
- Möbius Function
- 1
- Radical
- 15857
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- 102
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- Squarefree Number
- yes
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- a(n) = floor(2^n/(n^2)).at n=22A060505
- Numbers n such that n and its reversal are distinct brilliant numbers (A078972).at n=22A097435
- Both n and the reverse of n are brilliant numbers (A078972).at n=36A115655
- Positive numbers y such that y^2 is of the form x^2+(x+313)^2 with integer x.at n=8A160574
- Smallest m such that Fibonacci(2n-1) = m^2 + k^2.at n=24A229139
- a(n) = 991*n^2 + 1.at n=4A237991
- Number of length 5+2 0..n arrays with every three consecutive terms having the sum of some two elements equal to twice the third.at n=21A248438
- Bases b where exactly seven primes p with p < b exist such that p is a base-b Wieferich prime.at n=37A325883
- Number of integer partitions of n whose negated run-lengths are unimodal.at n=39A332638
- Numbers b > 1 such that the smallest four primes, i.e., 2, 3, 5 and 7 are base-b Wieferich primes.at n=16A339533
- Numbers m such that Stern polynomial B(m,x) has no irreducible polynomial factors that themselves are Stern polynomials. The initial a(1) = 1 is included by convention.at n=20A389918