13120
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 7
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 28
- Divisor Sum
- 32004
- Proper Divisor Sum (Aliquot Sum)
- 18884
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5120
- Möbius Function
- 0
- Radical
- 410
- Omega Function (Ω)
- 8
- 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
- 32
- 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
- yes
- Odd
- no
Appears in sequences
- Number of ways of writing n as a sum of 6 squares.at n=27A000141
- a(n) = n*(n+1)*(n+8)/6.at n=40A006503
- Record highest point of trajectory before reaching 1 in '3x+1' problem, corresponding to starting values in A006884.at n=6A006885
- 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 57.at n=29A031555
- Total number of possible knight moves on an (n+2) X (n+2) chessboard, if the knight is placed anywhere.at n=40A035008
- Number of Gnutella users reachable with given connections and hops.at n=62A067066
- m for which prime(m) is the least prime dividing #prime(n) - 1, i.e., one less than primorial n-th prime (A057588).at n=12A068489
- Largest term in periodic part of continued fraction expansion of square root of -1+3^n.at n=15A077627
- LCM of terms in periodic part of continued fraction expansion of square root of -1+3^n.at n=15A077635
- Maximal term in Collatz-iteration started at -1+2^n.at n=7A087701
- Inverse modulo 2 binomial transform of 3^n.at n=9A100736
- a(n) = 2*(3^n - 1).at n=8A100774
- Numbers n such that there exists at least one number j and pi(m) = d_1 d_2 ... d_j*d_(j+1) d_(j+2) ... d_k where d_1 d_2 ...d_k is the decimal expansion of n.at n=22A112012
- Number of palindromes (in base 3) below 3^n.at n=16A117862
- Number of palindromes (in base 9) below 9^n.at n=7A117868
- Greatest product of two numbers made up together of decimal digits 0 to n once.at n=3A125722
- Number of possible 2 X n arrangements of black and white squares that can form two consecutive rows in an n X n crossword puzzle.at n=8A133226
- Numbers with 28 divisors.at n=39A137491
- a(n) = phi(n)*T(n), where phi(n) is Euler's totient function (A000010) and T(n) = n*(n+1)/2 is the n-th triangular number (A000217).at n=39A143268
- Number of ways to place zero or more nonadjacent 1,0 1,1 2,1 2,2 3,1 4,1 5,1 6,1 polyhexes in any orientation on a planar nXnXn triangular grid.at n=7A155364