13281
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 18720
- Proper Divisor Sum (Aliquot Sum)
- 5439
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8352
- Möbius Function
- -1
- Radical
- 13281
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 76
- 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
- Sum of n plus its prime factors associated with A020700.at n=22A020905
- Number of solutions to c(1)*prime(3)+...+c(n)*prime(n+2) = 1, where c(i) = +-1 for i>1, c(1) = 1.at n=22A022901
- Numbers n such that A048767(n+1)=A048767(n).at n=18A048769
- Smallest number m such that the concatenation of n+1 numbers m^0, m^1,..., m^(n-1), m^n is a prime.at n=22A096469
- a(n) = 8*n^2 - 4*n - 3.at n=40A118057
- Number of n-cell fixed tree-like polycubes in 6 dimensions.at n=4A191096
- Dispersion of A016861, (5k+1), by antidiagonals.at n=39A191703
- Sum of the smallest parts of the partitions of 4n into 4 parts with smallest part greater than 1.at n=17A238706
- Numbers k such that the reverse of the first k digits in the decimal expansion of Pi forms a prime.at n=10A282183
- Expansion of Product_{k>=2} (1 - x^k)^k.at n=38A298599
- Odd composite integers m such that A006497(m) == 3 (mod m).at n=22A335669
- Odd composite integers m such that A087130(m) == 5 (mod m).at n=23A335671
- Odd composite integers m such that U(m)^2 == 1 (mod m) and V(m) == 3 (mod m), where U(m) and V(m) are the m-th generalized Lucas and Pell-Lucas numbers of parameters a=3 and b=-1, respectively.at n=14A337626
- Odd composite integers m such that U(m)^2 == 1 (mod m) and V(m) == 5 (mod m), where U(m) and V(m) are the m-th generalized Lucas and Pell-Lucas numbers of parameters a=5 and b=-1, respectively.at n=14A337628
- Numbers k whose ordered binary weights (A000120) of their divisors are the numbers 1 to A000005(k).at n=39A354724