3891
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 5192
- Proper Divisor Sum (Aliquot Sum)
- 1301
- 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
- 2592
- Möbius Function
- 1
- Radical
- 3891
- 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
- 38
- 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
- Coordination sequence T3 for Zeolite Code RSN.at n=41A009887
- a(n) = floor( n*(n-1)*(n-2)/25 ).at n=47A011907
- Exponential convolution of Fibonacci numbers with themselves (divided by 2).at n=9A014335
- a(n) = 5*a(n-1) - 2*a(n-2), with a(0)=2, a(1)=9.at n=5A020698
- a(n) = (n/2)*(n^4 + 1).at n=6A021003
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 40.at n=27A031538
- Numerators of continued fraction convergents to sqrt(166).at n=7A041306
- Numerators of continued fraction convergents to sqrt(664).at n=5A042276
- Base-6 palindromes that start with 3.at n=14A043012
- Numbers m such that string 9,1 occurs in the base 10 representation of m but not of m+1.at n=41A044804
- Numbers whose base-4 representation contains exactly two 0's and four 3's.at n=5A045075
- Discriminants of imaginary quadratic fields with class number 24 (negated).at n=37A048925
- a(n) = 1 + Sum_{i=1..n} phi(i)^2.at n=30A049454
- a(n) = Sum_{i=0..floor(n/2)} T(2i,n-2i), array T as in A049747.at n=28A049750
- Numbers k such that k^16 == 1 (mod 17^3).at n=9A056088
- Numbers k such that 7*(10^k - 1)/9 - 5*10^floor(k/2) is a palindromic wing prime (a.k.a. near-repdigit palindromic prime).at n=7A077777
- Number of compositions of n where the smallest part is greater than the number of parts.at n=40A098132
- a(1) = 393; for n > 1, a(n) = a(n-1) + 1 + sum of distinct prime factors of a(n-1) that are < a(n-1). edit.at n=30A105210
- Triangle read by rows: T(n,k) = n*(1+n^k)/2, 0<=k<=n.at n=25A108396
- Start with 1 and repeatedly reverse the digits and add 40 to get the next term.at n=23A118636