11901
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 15872
- Proper Divisor Sum (Aliquot Sum)
- 3971
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7932
- Möbius Function
- 1
- Radical
- 11901
- 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
- 50
- 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
- a(n) = n*(n-1) + (n-2)*(n-3) + ... + 1*0 + 1 for n odd; otherwise, a(n) = n*(n-1) + (n-2)*(n-3) + ... + 2*1.at n=40A014112
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 72.at n=34A031570
- 55 'Reverse and Add' steps are needed to reach a palindrome.at n=1A065322
- Centered 20-gonal (or icosagonal) numbers.at n=34A069133
- Expansion of 1/((1-x)^2*(1-x^2)^2*(1-x^3)*(1-x^4)^2*(1-x^5)).at n=24A069957
- a(n) = (3*5^n + (-3)^n)/4.at n=6A083231
- Least k such that 10^(2n-1)+k is a brilliant number.at n=35A084476
- Add/multiply sequence, see example.at n=40A093361
- a(0) = 1, a(n) = 1 + 2*3 + 4*5 + 6*7 + ... + (2n)*(2n+1) for n > 0.at n=20A098931
- Square array T(n, k) = Product_{j=1..n} ( Sum_{i=0..j-1} ( (k+1)^6 -(k+1)^5 -(k+1)^4 +(k+1)^2 )^i ) with T(n, 0) = n!, read by antidiagonals.at n=23A156889
- Integers k such that all the digits needed to write the consecutive nonnegative integers from 0 to k fill exactly a square (no holes, no overlaps).at n=39A158022
- L.g.f.: Sum_{n>=1} a(n)*x^n/n = Sum_{n>=1} x^n/n * exp( Sum_{k>=1} sigma(n*k)*x^(n*k)/k ).at n=17A203321
- Number n such that a2 - n^3 is a triangular number (A000217), where a2 is the least square above n^3.at n=32A233400
- Indices of primes followed by a gap (distance to next larger prime) of 42.at n=31A320719
- Array read by descending antidiagonals: T(n,k) is the number of achiral colorings of the facets of a regular n-dimensional orthoplex using up to k colors.at n=30A325015
- a(n) is the number of ways to express 2*n+1 as a sum of parts x such that x+2 is an odd prime.at n=39A333615
- Number of achiral colorings of the 8 triangular faces of a regular octahedron or the 8 vertices of a cube using n or fewer colors.at n=5A337897
- Numbers k such that lcm(1,2,3,...,k)/23 equals the denominator of the k-th harmonic number H(k).at n=20A342351
- Centered truncated octahedral numbers: the number of integer triples (x,y,z) such that max(|x|,|y|,|z|) <= 2n and |x|+|y|+|z| <= 3n.at n=7A371515
- a(n) = 76 + 275*n.at n=43A377165