15663
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 21888
- Proper Divisor Sum (Aliquot Sum)
- 6225
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9944
- Möbius Function
- -1
- Radical
- 15663
- 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
- 177
- 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
- a(n) = Fibonacci(n) - 2^(floor(n/2)).at n=22A028892
- Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 19 (most significant digit on right).at n=23A061972
- Fibonacci bisection minus powers of 2.at n=11A139209
- Number of n X n binary arrays symmetric under 90 degree rotation with all ones connected only in a 00100-00100-11111-00100 pattern in any orientation.at n=17A147330
- Number of -2..2 arrays of n elements with first and second differences also in -2..2.at n=7A201082
- T(n,k)=Number of -k..k arrays of n elements with first and second differences also in -k..k.at n=43A201088
- Numbers k such that (19*10^k + 101) / 3 is prime.at n=22A276672
- a(n) = a(n-1) + 3*a(n-2) -2*a(n-3) - 2*a(n-4), where a(0) = -1, a(1) = -1, a(2) = 0, a(3) = 1.at n=18A295731
- Number of nX2 0..1 arrays with every element unequal to 0, 1, 2, 3 or 5 king-move adjacent elements, with upper left element zero.at n=8A304304
- T(n,k)=Number of nXk 0..1 arrays with every element unequal to 0, 1, 2, 3 or 5 king-move adjacent elements, with upper left element zero.at n=46A304310
- T(n,k)=Number of nXk 0..1 arrays with every element unequal to 0, 1, 2, 3, 5 or 6 king-move adjacent elements, with upper left element zero.at n=46A305593
- T(n,k)=Number of nXk 0..1 arrays with every element unequal to 0, 1, 2, 3, 5 or 7 king-move adjacent elements, with upper left element zero.at n=46A305776
- T(n,k)=Number of nXk 0..1 arrays with every element unequal to 0, 1, 2, 3, 5 or 8 king-move adjacent elements, with upper left element zero.at n=46A316209
- T(n,k)=Number of nXk 0..1 arrays with every element unequal to 0, 1, 2, 3, 5, 6 or 7 king-move adjacent elements, with upper left element zero.at n=46A316876
- T(n,k)=Number of nXk 0..1 arrays with every element unequal to 0, 1, 2, 3, 5, 6 or 8 king-move adjacent elements, with upper left element zero.at n=46A317011
- T(n,k)=Number of nXk 0..1 arrays with every element unequal to 0, 1, 2, 3, 5, 7 or 8 king-move adjacent elements, with upper left element zero.at n=46A317125
- T(n,k)=Number of nXk 0..1 arrays with every element unequal to 0, 1, 2, 3, 5, 6, 7 or 8 king-move adjacent elements, with upper left element zero.at n=46A317604
- Regular triangle where T(n,k) is the number of pairs of set partitions of {1,...,n} with join of length k.at n=16A318392
- Numbers of the form ab such that phi(ab) = a*b - 1 where ab is the concatenation of a and b.at n=2A336192
- G.f. A(x) satisfies: A(x) = x - x^2 * exp(A(x) - A(x^2)/2 + A(x^3)/3 - A(x^4)/4 + ...).at n=22A363087