15127
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 17296
- Proper Divisor Sum (Aliquot Sum)
- 2169
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12960
- Möbius Function
- 1
- Radical
- 15127
- 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
- yes
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 84
- 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
- Lucas numbers (beginning with 1): L(n) = L(n-1) + L(n-2) with L(1) = 1, L(2) = 3.at n=19A000204
- a(n) = 11*a(n-1) + a(n-2).at n=4A001946
- a(n) = round(n*phi^20), where phi is the golden ratio, A001622.at n=1A004955
- a(n) = ceiling(n*phi^20), where phi is the golden ratio, A001622.at n=1A004975
- a(n) = 3*a(n-2) - a(n-4), a(0)=2, a(1)=1, a(2)=3, a(3)=2. Alternates Lucas (A000032) and Fibonacci (A000045) sequences for even and odd n.at n=20A005247
- Bisection of Lucas numbers: a(n) = L(2*n) = A000032(2*n).at n=10A005248
- a(n) = floor( n*(n-1)*(n-2)/19 ).at n=67A011901
- Odd Lucas numbers.at n=13A014447
- Number of maximum matchings in the n-Moebius ladder M_n.at n=20A020878
- a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = (Lucas numbers), t = A023533.at n=53A024476
- a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n-k+1), where k = floor(n/2), s = A000032, t = A023533.at n=52A025096
- Numerators of continued fraction convergents to sqrt(45).at n=9A041076
- Numerators of continued fraction convergents to sqrt(125).at n=5A041226
- Denominators of continued fraction convergents to sqrt(427).at n=8A041813
- Numerators of continued fraction convergents to sqrt(605).at n=7A042160
- a(n) = Lucas(4*n).at n=5A056854
- Fibonacci-type sequence based on subtraction: a(0) = 1, a(1) = 2 and a(n) = a(n-2) - a(n-1).at n=21A061084
- a(n) = floor(tau^n) + 1, where tau = (1 + sqrt(5))/2.at n=20A062724
- Squarefree Lucas numbers.at n=15A063509
- a(n) = gcd(1 + Fibonacci(n+1), 1 + Fibonacci(n)).at n=41A063726