15955
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 25
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 19152
- Proper Divisor Sum (Aliquot Sum)
- 3197
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12760
- Möbius Function
- 1
- Radical
- 15955
- 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
- 53
- 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
- Conjecturally, number of infinitely-recurring prime patterns on n consecutive integers.at n=35A023192
- Convolution of A007054 (Super ballot numbers) with A000302 (powers of 4).at n=6A038679
- Numbers k such that 6^k - 5 is prime.at n=21A059614
- G.f. = continued fraction: A(x)=1/(1-x^2-x/(1-x^2-x^2/(1-x^2-x^3/(1-x^2-x^4/(...))))).at n=13A088356
- Numbers k such that 2*10^k+9 is prime.at n=8A101392
- Numbers n such that 4*10^n + 7*R_n - 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.at n=4A102995
- Triangular matrix T, read by rows, that satisfies: [T^-1](n,k) = -(k+1)*T(n-1,k) when (n-1)>=k>=0, with T(n,n) = 1 and T(n+1,n) = (n+1) for n>=0.at n=40A106208
- Number of partitions that are "3-close" to being self-conjugate.at n=44A108962
- Number of n-lobsters.at n=15A130131
- Number of 2X3 integer matrices with each row summing to zero, row elements in nondecreasing order, rows in lexicographically nondecreasing order, and the sum of squares of the elements <= 2*n^2 (number of collections of 2 zero-sum 3-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations).at n=19A192698
- Erroneous version of A130131.at n=15A338355
- a(n) = Sum_{k=0..n} binomial(n,k) * binomial(2*n+4*k,k).at n=4A388727