13761
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
- 12
- Divisor Sum
- 21840
- Proper Divisor Sum (Aliquot Sum)
- 8079
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8280
- Möbius Function
- 0
- Radical
- 4587
- Omega Function (Ω)
- 4
- 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
- 151
- 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
- a(n) = (d(n)-r(n))/2, where d = A026037 and r is the periodic sequence with fundamental period (1,0,0,1).at n=41A026038
- Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 5-point zee 1,1 2,1 2,2 2,3 3,3 in any orientation.at n=9A146070
- 28-gonal numbers: a(n) = n*(13*n - 12).at n=33A161935
- Numbers n such that n+/-2 and n^2+/-2 are all primes.at n=13A189051
- Number of equivalence classes of Dyck paths of semilength n for the string udu.at n=12A274289
- a(n) = A277713(n)/3.at n=53A277714
- Expansion of Product_{k>0} (1 - q^(3*k))^5/((1 - q^k)^3*(1 - q^(6*k))^2).at n=17A293423
- Least k for the inner Theodorus spiral to complete n revolutions.at n=36A295339
- Number of series-reduced rooted trees whose leaves are integer partitions whose multiset union is an integer partition of n.at n=8A319312
- Euler transform of 2^floor(n/2), (A016116).at n=16A358369
- Zeroless analog of tribonacci numbers.at n=44A371911
- Gaston Tarry's 1905 trimagic square of order 128, read by rows.at n=10A381002
- Numbers k such that A003415(k) == A276085(k) (mod 5^5), where A003415 is the arithmetic derivative and A276085 is the primorial base log-function.at n=12A391865