7381
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 6
- Divisor Sum
- 8246
- Proper Divisor Sum (Aliquot Sum)
- 865
- 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
- 6600
- Möbius Function
- 0
- Radical
- 671
- Omega Function (Ω)
- 3
- 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
- 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
- 39
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- a(n) = numerator of harmonic number H(n) = Sum_{i=1..n} 1/i.at n=9A001008
- a(n) = (9^n - 1)/8.at n=5A002452
- Pseudoprimes to base 3.at n=20A005935
- Coloring a circuit with 4 colors.at n=9A006342
- Triangle of central factorial numbers 4^k T(2n+1, 2n+1-2k).at n=19A008958
- a(n) = (2*n+1)*(4*n+1).at n=30A014634
- q-Fibonacci numbers for q=9, scaling a(n-2).at n=5A015467
- Cyclotomic polynomials at x=9.at n=5A019327
- Pseudoprimes to base 9.at n=44A020138
- Pseudoprimes to base 27.at n=44A020155
- Pseudoprimes to base 40.at n=28A020168
- Strong pseudoprimes to base 9.at n=12A020235
- Strong pseudoprimes to base 81.at n=17A020307
- Cyclotomic polynomials at x=-9.at n=10A020508
- Triangle of Gaussian binomial coefficients [ n,k ] for q = 9.at n=16A022173
- Triangle of Gaussian binomial coefficients [ n,k ] for q = 9.at n=19A022173
- Gaussian binomial coefficients [ n,4 ] for q = 9.at n=1A022255
- a(n) = (1/1 + 1/2 + ... + 1/n)*lcm{1,2,...,n}.at n=9A025529
- Triangle read by rows: square of the lower triangular mean matrix.at n=45A027446
- Numbers k such that k^2 is palindromic in base 9.at n=16A029994