3821
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 3822
- Proper Divisor Sum (Aliquot Sum)
- 1
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 3820
- Möbius Function
- -1
- Radical
- 3821
- 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
- 30
- 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
- 530
- 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=11A001135
- Number of different shapes formed by bending a piece of wire of length n in the plane.at n=10A001997
- From a Goldbach conjecture: records in A185091.at n=31A002092
- Numbers n such that n, 2n+1, and 4n+3 all prime.at n=26A007700
- Numbers k such that the continued fraction for sqrt(k) has period 27.at n=13A020366
- Let q_k=p(p+2) be product of k-th pair of twin primes; sequence gives values of p such that (q_k)^2 > q_{k-i}q_{k+i} for all 1 <= i <= k-1.at n=32A021005
- Primes that remain prime through 2 iterations of function f(x) = 3x + 8.at n=38A023248
- Primes that remain prime through 2 iterations of function f(x) = 4x + 3.at n=45A023250
- Upper prime of a difference of 18 between consecutive primes.at n=9A031937
- The 20 primes inside the 4 X 4 matrix with all the rows, columns and major diagonals being reversible non-palindromic and distinct primes (the smallest prime-magical square): [ 1933, 1283, 9551, 3719 ].at n=10A032530
- Zeckendorf expansion of n: repeatedly subtract the largest Fibonacci number you can until nothing remains. Little-endian concatenation of decimals.at n=32A035515
- Basic numbers used in Sedgewick-Incerpi upper bound for shell sort.at n=9A036567
- Number of partitions satisfying cn(2,5) + cn(3,5) <= 1.at n=37A039857
- Primes p such that p+2 and 2p+1 are also prime.at n=32A045536
- Discriminants of real quadratic fields with class number 1 and related continued fraction period length of 17.at n=8A050966
- Smallest prime in n-th shell of prime spiral.at n=12A053998
- Concatenation of n in base 2 up to base 10 is prime, all numbers are interpreted as decimals.at n=43A054256
- Sum of a(n) terms of 1/k^(7/8) first exceeds n.at n=15A056184
- Number of points of rotation in a prime block spiral.at n=45A059428
- Primes p such that p^7 reversed is also prime.at n=28A059700