16561
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- yes
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 16562
- 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
- 16560
- Möbius Function
- -1
- Radical
- 16561
- 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
- 159
- 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
- 1917
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Palindromic primes: prime numbers whose decimal expansion is a palindrome.at n=37A002385
- Quartan primes: primes of the form x^4 + y^4, x > 0, y > 0.at n=19A002645
- Octal palindromes which are also primes.at n=25A006341
- 4-dimensional centered cube numbers.at n=9A008514
- Palindromic in bases 7 and 10.at n=12A029964
- Palindromic primes in which parity of digits alternates.at n=16A030150
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 74 ones.at n=15A031842
- Lesser of two consecutive palindromes, both of which are prime.at n=10A032593
- Numerators of continued fraction convergents to sqrt(230).at n=3A041428
- Numerators of continued fraction convergents to sqrt(920).at n=3A042778
- Numbers whose base-7 representation contains exactly four 6's.at n=13A043420
- Numbers whose base-5 representation contains exactly three 1's and three 2's.at n=23A045232
- Primes that are palindromic in bases 7 and 10.at n=3A046476
- Palindromic primes containing no pair of consecutive equal digits.at n=32A050784
- Number of binary arrangements on n X n array without three adjacent 1's in a row or column.at n=4A050974
- Euclid-Mullin sequence (A000945) with initial value a(1)=31 instead of a(1)=2.at n=22A051315
- Primes p such that x^18 = 2 has no solution mod p, but x^6 = 2 has a solution mod p.at n=32A059664
- Primes p such that x^54 = 2 has no solution mod p, but x^6 = 2 has a solution mod p.at n=34A059665
- Primes of the form 2*n^2 - 1.at n=41A066436
- Primes that can be formed by concatenating 2^a and 3^b.at n=29A068801