3945
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
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 6336
- Proper Divisor Sum (Aliquot Sum)
- 2391
- 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
- 2096
- Möbius Function
- -1
- Radical
- 3945
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 3
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
- 100
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- Number of primes < prime(n)^2.at n=43A000879
- Coordination sequence T1 for Zeolite Code ZON.at n=44A009919
- Coordination sequence T4 for Zeolite Code ZON.at n=44A009922
- Expansion of 1/(1-x^4-x^5-x^6-x^7-x^8-x^9).at n=34A017831
- a(n) = Sum_{k=0..n-1} T(n,k)*T(n,k+1), T given by A026736.at n=6A027216
- Numbers k such that 81*2^k+1 is prime.at n=42A032390
- Concatenation of n and n + 6 or {n,n+6}.at n=38A032611
- a(n) = a(n-1) + a(round(2*(n-1)/3)) + a(round((n-1)/3)) with a(1)=a(2)=1.at n=28A033499
- Decimal part of cube root of a(n) starts with 8: first term of runs.at n=14A034134
- Number of partitions of n such that cn(0,5) = cn(1,5) < cn(2,5) = cn(4,5) <= cn(3,5).at n=63A036870
- a(n)=T(n,n+2), array T as in A049735.at n=24A049742
- a(n) = a(n-1) + a(m) for n >= 4, where m = 2^(p+1) + 2 - n and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1 and a(2) = a(3) = 3.at n=37A050065
- Handsome numbers (A007532) representable as a sum of any positive powers of their digits in two distinct ways, not counting different powers of duplicated digits as distinct.at n=28A050240
- 11-gonal (or hendecagonal) numbers: a(n) = n*(9*n-7)/2.at n=30A051682
- Sum of numbers in range 10*n to 10*n+9.at n=39A053743
- Integers n > 879 such that the 'Reverse and Add!' trajectory of n joins the trajectory of 879.at n=18A063052
- Exponents in expansion of constant A065479 as a product zeta(n)^(-a(n)).at n=15A065491
- Exponents in expansion of constant A065480 as a product zeta(n)^(-a(n)).at n=15A065492
- Sum of the remainders when n^2 is divided by squares less than n.at n=31A067459
- Interprimes which are of the form s*prime, s=15.at n=21A075290