16661
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- yes
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 16662
- Proper Divisor Sum (Aliquot Sum)
- 1
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 16660
- Möbius Function
- -1
- Radical
- 16661
- 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
- 128
- 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
- 1928
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes p such that the multiplicative order of 2 modulo p is (p-1)/5.at n=41A001135
- Palindromic primes: prime numbers whose decimal expansion is a palindrome.at n=38A002385
- Primes that contain digits 1 and 6 only.at n=6A020454
- Least k such that first k terms of A022300 contain n more 2's than 1's.at n=26A025515
- Numbers k such that 155*2^k+1 is prime.at n=19A032454
- Greater of two consecutive palindromes, both of which are prime.at n=10A032594
- Sums of 5 distinct powers of 4.at n=22A038473
- Palindromic and prime Fibonacci-lucky numbers.at n=16A039679
- Primes that yield a different prime when rotated by 180 degrees.at n=39A048890
- Palindromic primes containing at least one pair of consecutive equal digits.at n=5A050786
- Beastly (or hateful) numbers: numbers containing the string 666 in their decimal expansion.at n=26A051003
- Palindromic primes using only two distinct digits and only the exterior digit is different.at n=17A056728
- Palindromic primes with just two distinct digits.at n=19A056730
- Primes which can be expressed as concatenation of powers of 6 and 0's.at n=22A066597
- Primes in which a string of 6's is sandwiched between two 1's.at n=1A068647
- Primes which are a sandwich of numbers using at most one digit between two 1's.at n=8A068685
- Numbers n such that phi(n) + sigma(n) = n + reversal(n).at n=39A069217
- Primes with either no internal digits or all internal digits are 6.at n=51A069681
- Numbers n for which there are exactly seven k such that n = k + reverse(k).at n=31A072431
- Palindromic primes with nonprime middle digit.at n=16A076613