7781
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 23
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 8064
- Proper Divisor Sum (Aliquot Sum)
- 283
- 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
- 7500
- Möbius Function
- 1
- Radical
- 7781
- 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
- 39
- 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
- Maximal number of pairwise relatively prime polynomials of degree n over GF(2).at n=17A001115
- Divisors of 2^50 - 1.at n=17A003554
- a(n) = 10000*log_10(n) rounded down.at n=5A004228
- Numbers k such that the continued fraction for sqrt(k) has period 72.at n=29A020411
- dot_product(n,n-1,...2,1)*(7,8,...,n,1,2,3,4,5,6).at n=24A026066
- (nextprime(5^n)-nextprime(2^n))/2.at n=6A037133
- Numerators of continued fraction convergents to sqrt(59).at n=6A041102
- Numbers having four 0's in base 6.at n=9A043372
- Numbers whose base-5 representation contains exactly three 1's and three 2's.at n=19A045232
- Total number of parts which are positive powers of 2 in all partitions of n.at n=26A073119
- Number of positions that are exactly n moves from the starting position in the Bicube or Bandaged Rubik's Cube puzzle.at n=25A079771
- Triangle read by rows in which the n-th row contains n distinct numbers whose sum is n^n. The numbers are terms of an arithmetic progression with a common difference 1 or 2 respectively accordingly as n is odd or even.at n=20A080524
- Final entry in n-th row of triangle in A080524.at n=5A080526
- a(1) = 1; a(n) = max{ 5*a(k) + a(n-k) | 1 <= k <= n/2 } for n > 1.at n=32A130667
- a(n) = n*(8*n+3).at n=31A139276
- Numerators of partial sums of a certain alternating series of inverse central binomial coefficients.at n=4A145559
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, 0, 1), (0, 0, 1), (0, 1, 0), (1, -1, 1), (1, 1, -1)}.at n=7A150268
- Number of permutations of length n which avoid the patterns 4123 and 3412.at n=8A165544
- a(n) = A030068(4n+3).at n=37A169740
- a(n) = n^(n-1) + n - 1.at n=5A173235