6441
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
- 4
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 9120
- Proper Divisor Sum (Aliquot Sum)
- 2679
- 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
- 4032
- Möbius Function
- -1
- Radical
- 6441
- 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
- yes
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- yes
- 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
- 124
- 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
- Expansion of 1/(1-x^2-x^3-x^4-x^5-x^6-x^7-x^8-x^9-x^10).at n=21A013987
- a(n) = (2*n+1)*(4*n+1).at n=28A014634
- Pseudoprimes to base 56.at n=34A020184
- Pseudoprimes to base 77.at n=29A020205
- a(n) = position of 3*n^3 in A003072.at n=26A024970
- (prime(n)-1)(prime(n)-3)/8.at n=48A030005
- Graham-Sloane-type lower bound on the size of a ternary (n,3,4) constant-weight code.at n=25A030504
- Triangular numbers (A000217) with prime indices.at n=29A034953
- Odd triangular numbers with prime indices.at n=14A034954
- Number of partitions of n with equal number of parts congruent to each of 1 and 2 (mod 4).at n=44A035543
- G.f.: (1-2*x*c(x))/(1-3*x*c(x)) where c(x) = (1 - sqrt(1-4*x))/(2*x) is the g.f. for Catalan numbers A000108.at n=7A049027
- a(n) = 4*n^2 - 7*n + 4.at n=40A054567
- Fifth spoke of a hexagonal spiral.at n=46A056109
- a(n) = (prime(n)^2 - 1)/8.at n=47A061066
- Staircase of coefficients of polynomials used for column g.f.s of triangle A060923.at n=32A061186
- Smallest triangular number that contains the string n in its exact center.at n=44A062690
- 3 times pentagonal numbers: 3*n*(3*n-1)/2.at n=38A062741
- Square array read by antidiagonals: T(n,k)=(T(n,k-1)*n^2-Catalan(k-1))/(n-1) with a(n,1)=1 and a(1,k)=Catalan(k) where Catalan(k)=C(2k,k)/(k+1)=A000108(k).at n=38A067345
- Triangular numbers with sum of digits = 15.at n=19A068130
- Smallest triangular number with value of the internal digits = n; or 0 if no such number exists.at n=44A069692