16531
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 16864
- Proper Divisor Sum (Aliquot Sum)
- 333
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 16200
- Möbius Function
- 1
- Radical
- 16531
- 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
- 141
- 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
- Pseudoprimes to base 3.at n=31A005935
- Strong pseudoprimes to base 3.at n=8A020229
- Strong pseudoprimes to base 9.at n=21A020235
- Strong pseudoprimes to base 19.at n=17A020245
- Strong pseudoprimes to base 27.at n=20A020253
- Strong pseudoprimes to base 57.at n=15A020283
- Strong pseudoprimes to base 81.at n=31A020307
- Numbers that, when expressed in base 7 and then interpreted in base 10, yield a multiple of the original number.at n=37A032549
- a(n) = (2*n+1)*(9*n+1).at n=30A033573
- Multiplicity of highest weight (or singular) vectors associated with character chi_92 of Monster module.at n=39A034480
- Base-3 Euler-Jacobi pseudoprimes.at n=13A048950
- Numbers k that, when expressed in base 7 and then interpreted in base 10, give a multiple of k.at n=38A062944
- Numbers k such that 100k+1, 100k+3, 100k+7, 100k+9 are all primes.at n=26A064687
- Numbers n such that sum of squares of even digits of n equals sum of squares of odd digits of n.at n=28A076164
- Largest proper divisor of the n-th Carmichael number (A002997).at n=32A081703
- Number of ordered quintuples (a,b,c,d,e) with gcd(a,b,c,d,e)=1 (1<= {a,b,c,d,e} <= n).at n=6A082544
- Composite numbers such that all divisors >1 have the same number of 1's in binary representation.at n=34A089042
- a(n) = 5*n^4 - 10*n^3 + 20*n^2 - 15*n + 11.at n=7A115565
- Nonprimes k such that 3^k == 3 (mod k).at n=39A122780
- Terms of A122780 which are not Carmichael numbers A002997.at n=30A153514