6391
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
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 8064
- Proper Divisor Sum (Aliquot Sum)
- 1673
- 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
- 4920
- Möbius Function
- -1
- Radical
- 6391
- 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
- 75
- 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
- Hexagonal pyramidal numbers, or greengrocer's numbers.at n=21A002412
- Expansion of 1/((1-x)^4*(1+x)).at n=40A002623
- a(n) = n^2 written backwards.at n=43A002942
- Odd hexagonal pyramidal numbers.at n=10A015225
- a(n) = 1*(n) + 2*(n-1) + 3*(n-2) + ... + (n+1-k)*k, where k = floor((n+1)/2).at n=40A023855
- Number of partitions of n that do not contain 7 as a part.at n=32A027341
- "AFJ" (ordered, size, labeled) transform of 1,2,3,4,...at n=7A032002
- Floor(X/Y) where X = concatenation of (n+1), (n+2), ...up to 2n and Y = concatenation of 1,2,3,4,... up to n.at n=5A067088
- n^2 read backwards, for n = 51, 50, 49, ..., 1.at n=7A080334
- Number of naturally embedded binary trees with n nodes that have no label greater than 0.at n=11A101488
- Square array T(n,k), read by antidiagonals: number of binary trees, with n nodes that have no label greater than k.at n=76A101489
- Square array T(n,k), read by antidiagonals: number of binary trees, with n nodes that have no label greater than k.at n=77A101489
- Numbers k such that k^6+6 is prime.at n=31A109836
- Second bisection of A061039.at n=38A144450
- Numerator of Euler(n, 9/25).at n=3A156978
- Products of 3 distinct safe primes.at n=17A157354
- Numbers with distinct digits appearing in partition of decimal expansion of e (A001113).at n=31A167836
- Partial sums of A002620.at n=42A173196
- A185128(n) is the a(n)-th triangular number.at n=39A185223
- Largest possible side length for a perfect squared square of order n; or 0 if no such square exists.at n=32A217149