3921
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 5232
- Proper Divisor Sum (Aliquot Sum)
- 1311
- 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
- 2612
- Möbius Function
- 1
- Radical
- 3921
- 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
- 51
- 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
- Number of 3 X 3 X 3 arrays M_ijk (1 <= i,j,k <= 3) with entries satisfying 0 <= M_ijk <= n and all line sums equal to n.at n=4A002721
- Coordination sequence T3 for Zeolite Code EUO.at n=39A008098
- Coordination sequence T2 for Zeolite Code NON.at n=38A008213
- Integers that are squarefree and also the sum of first k squarefrees for some k.at n=41A013932
- Numbers k such that the continued fraction for sqrt(k) has period 80.at n=10A020419
- a(n) = [ a(n-1)/a(1) ] + [ a(n-3)/a(3) ] + [ a(n-5)/a(5) ] + ..., for n >= 3.at n=31A022878
- Coordination sequence T3 for Zeolite Code ITE.at n=43A027371
- Numbers k that divide the (right) concatenation of all numbers <= k written in base 3 (most significant digit on left).at n=18A029448
- Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 19 (most significant digit on right).at n=23A029512
- 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=29A031538
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 38 ones.at n=7A031806
- Multiplicity of highest weight (or singular) vectors associated with character chi_32 of Monster module.at n=38A034420
- Number of partitions of n into parts not of the form 17k, 17k+5 or 17k-5. Also number of partitions with at most 4 parts of size 1 and differences between parts at distance 7 are greater than 1.at n=30A035966
- Numerators of continued fraction convergents to sqrt(252).at n=4A041472
- The sequence e when b=[ 1,1,0,1,1,... ].at n=41A042955
- Number of nonempty subsets of {1,2,...,n} in which exactly 1/3 of the elements are <= (n-2)/2.at n=14A047183
- Number of nonempty subsets of {1,2,...,n} in which exactly 1/3 of the elements are <= (n+3)/3.at n=14A048083
- Positions in decimal expansion of Pi where next prime begins.at n=20A053013
- Let Py(n)=A000330(n)=n-th square pyramidal number. Consider all integer triples (i,j,k), j >= k>0, with Py(i)=Py(j)+Py(k), ordered by increasing i; sequence gives k values.at n=31A053721
- Numbers k such that 2*9^k + 1 is prime.at n=17A056802