15511
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 15512
- Proper Divisor Sum (Aliquot Sum)
- 1
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 15510
- Möbius Function
- -1
- Radical
- 15511
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- yes
- 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
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 1811
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Motzkin numbers: number of ways of drawing any number of nonintersecting chords joining n (labeled) points on a circle.at n=12A001006
- Primes that contain digits 1 and 5 only.at n=6A020453
- A bisection of the Motzkin numbers A001006.at n=6A026945
- First term of strong prime quintets: p(m+1)-p(m) > p(m+2)-p(m+1) > p(m+3)-p(m+2) > p(m+4)-p(m+3).at n=35A054808
- Number of asymmetric types of (4,n)-hypergraphs without isolated nodes, under action of symmetric group S_4; asymmetric n-covers of an unlabeled 4-set.at n=5A055539
- Table where the entry (n,k) (n >= 0, k >= 0) gives number of Motzkin paths of the length n with the minimum peak width of k.at n=78A064645
- Primes which can be expressed as concatenation of powers of 5 and 0's.at n=20A066596
- Expansion of (1 + x - sqrt(1 - 2*x - 3*x^2)) / 2 in powers of x.at n=14A086246
- Primes with at least four digits such that sum of any three_neighbor_digits is prime; first and last digits are neighbors.at n=38A086259
- Triangle read by rows: T(n,k)=number of ordered trees with n edges and k branch nodes at odd height.at n=30A091958
- Triangle read by rows: T(n,k) is the number of Dyck paths of semilength n having exactly k UUU's (triple rises) where U=(1,1). Rows have 1,1,1,2,3,4,5,... entries, respectively.at n=57A092107
- Prime Motzkin numbers (see A001006).at n=2A092832
- Number of (s(0), s(1), ..., s(n)) such that 0 < s(i) < 8 and |s(i) - s(i-1)| <= 1 for i = 1,2,...,n, s(0) = 1, s(n) = 1.at n=12A094288
- Triangle read by rows: counts Motzkin paths by length of final descent.at n=50A098979
- Triangle read by rows: counts Motzkin paths by length of final descent.at n=49A098979
- Triangle read by rows: T(n,k) is the number of short bushes with n edges and having the leftmost leaf at height k (a short bush is an ordered tree with no nodes of outdegree 1).at n=42A106489
- Triangle read by rows: T(n,k) is number of Grand Motzkin paths of length n having k returns to the x-axis from above (i.e., d steps hitting the x-axis).at n=42A109195
- Primes in which the frequency of every digit is also prime.at n=9A113615
- Lucky numbers for which both the sum of the digits and the product of the digits is also a lucky number.at n=33A118559
- Triangle read by rows: T(n,k) is the number of paths in the first quadrant from (0,0) to (n,0), consisting of steps U=(1,1), D=(1,-1), h=(1,0) and H=(2,0), having k H steps (0<=k<=floor(n/2)).at n=42A132280