11781
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 22464
- Proper Divisor Sum (Aliquot Sum)
- 10683
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5760
- Möbius Function
- 0
- Radical
- 3927
- Omega Function (Ω)
- 5
- Little Omega Function (ω)
- 4
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- yes
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- yes
- 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
- 81
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- Doubly triangular numbers: a(n) = n*(n+1)*(n^2+n+2)/8.at n=17A002817
- Representation degeneracies for boson strings.at n=32A005292
- Molien series for cyclic group of order 5.at n=32A008646
- Let j = | i - i_written_backwards |, k = j + j_written_backwards; then k is in this sequence.at n=44A008920
- a(n) = floor(C(n,4)/5).at n=36A011795
- a(n) = (2*n+1)*(4*n+1).at n=38A014634
- Odd octagonal numbers: (2n+1)*(6n+1).at n=31A014641
- a(n+2) = 3*a(n) - a(n-2) with a(0) = 1, a(1) = 3, a(2) = 6.at n=15A018186
- Quotients k*(k+1)*(k+2) / (k+(k+1)+(k+2)) that are lucky numbers.at n=14A032792
- Number of diagonal dissections of an n-gon into 3 regions.at n=17A033275
- Octagonal triangular numbers.at n=2A046183
- Octagonal hexagonal numbers.at n=1A046192
- a(n) = T(n,5), array T as in A051168; a count of Lyndon words; aperiodic necklaces with 5 black beads and n-5 white beads.at n=32A051170
- Maximal value of products of partitions of n into powers of distinct primes (powers of 1 and 2 excluded).at n=44A051704
- Smallest number which is the sum of two positive triangular numbers in exactly n different ways.at n=7A052346
- Expansion of (1-x^2)/(1-3*x-x^2).at n=8A052906
- Numbers that are n-gons for three or more n's, where n=3,4,5,...,16.at n=10A062712
- a(n) = the least integer that is polygonal in exactly n ways.at n=8A063778
- Smallest triangular number which is a multiple (>1) of the n-th triangular number.at n=32A068084
- Triangular numbers which are products of triangular numbers larger than 1.at n=19A068143