12821
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- yes
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 12822
- 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
- 12820
- Möbius Function
- -1
- Radical
- 12821
- 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
- 63
- 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
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- yes
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 1528
- 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=27A002385
- Strobogrammatic primes: the same upside down (calculator-style numerals).at n=10A018847
- Primes that remain prime through 3 iterations of function f(x) = 9x + 10.at n=37A023299
- a(n) = Sum_{k=0..2n-2} T(n,k) * T(n,k+2), with T given by A027023.at n=4A027048
- Greater of two consecutive palindromes, both of which are prime.at n=7A032594
- Largest palindromic substring in 4^n.at n=51A046262
- Largest palindromic substring in 8^n.at n=34A046266
- Palindromic primes containing no pair of consecutive equal digits.at n=24A050784
- Palindromic Sophie Germain primes.at n=6A051835
- Primes p such that p^12 reversed is also prime.at n=38A059705
- Initial primes of Cunningham chains of first type with length exactly 3. Primes in A059453 that survive as primes just two "2p+1 iterations", forming chains of exactly 3 terms.at n=29A059762
- Lesser of twin primes whose average is 6 times a prime.at n=31A060213
- Palindromic primes with strictly increasing digits up to the middle and then strictly decreasing.at n=16A062351
- Numbers n such that phi(n) + sigma(n) = n + reversal(n).at n=28A069217
- Numbers n of the form k + reverse(k) for exactly three k.at n=29A071914
- Primes which can be represented as the sum of a number and its reverse.at n=34A072382
- Palindromic primes with nonprime middle digit.at n=11A076613
- Palindromic primes = 1 mod 4.at n=14A081220
- n-th largest palindrome whose digit sum is n.at n=13A082265
- Palindromic primes with middle digit 8.at n=3A082444