16861
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- yes
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 18172
- Proper Divisor Sum (Aliquot Sum)
- 1311
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 15552
- Möbius Function
- 1
- Radical
- 16861
- 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
- 159
- 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
- Numbers n for which there are exactly seven k such that n = k + reverse(k).at n=32A072431
- In base 4, n sets a new record for the number of Reverse and Add! steps needed to reach a palindrome starting with n.at n=10A075686
- In base 4, smallest number that requires n Reverse and Add! steps to reach a palindrome.at n=37A077441
- a(1) = 1; then the smallest number such that both the forward and reverse n-th partial concatenation is a prime for n > 1. (Reverse concatenation is taken term-wise and not digit-wise.)at n=31A083992
- a(n) = 9*n^3 - 18*n^2 + 10*n.at n=13A086605
- Palindromic hypotenuses in primitive Pythagorean triples.at n=27A087456
- a(1) = 2; then least palindrome greater than the previous term such that every partial concatenation is a prime.at n=12A088084
- a(1) = 1, then the rearrangement of odd palindromes such that every concatenation is a prime for n > 1.at n=46A113578
- Palindromic composites such that some digit permutation is prime.at n=41A119378
- Palindromic mountain numbers.at n=32A173070
- Smallest k such that 33^k mod k = n.at n=20A178194
- Palindromic in bases 10 and 36.at n=27A250412
- Palindromes with no palindromic aliquot parts except 1.at n=17A257973
- Sum of median parts of all partitions of n into an odd number of distinct parts.at n=51A268359
- E.g.f.: exp(x + 2*x^2 + 3*x^3 + 4*x^4).at n=6A293717
- Square array A(n,k), n >= 0, k >= 1, read by antidiagonals, where column k is the expansion of e.g.f. exp(Sum_{j=1..k} j*x^j).at n=51A293718
- a(1) = 1, a(2) = 2; for n >= 3, a(n) = (n-1)^3 - a(n-1) - a(n-2).at n=36A361134