12661
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
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 13824
- Proper Divisor Sum (Aliquot Sum)
- 1163
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 11500
- Möbius Function
- 1
- Radical
- 12661
- 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
- 81
- 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
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 62 ones.at n=24A031830
- Composite numbers whose prime factors contain no digits other than 1 and 5.at n=19A036305
- a(n) = Sum_{k=0..n} binomial(2*n-2*k,n-k)^2 * binomial(n,k)^2.at n=4A036916
- Molien series for group G_{1,2}^{8} of order 1536.at n=30A051462
- Expansion of series related to Liouville's Last Theorem: g.f. sum_{t>0} (-1)^(t+1) *x^(t*(t+1)/2) / ( (1-x^t)^8 *product_{i=1..t} (1-x^i) ).at n=9A059825
- a(0) = 0. If n is odd, a(n) = a(n-1) + n, otherwise a(n) = a(n-1) * n.at n=11A077138
- Starting positions of strings of three 7's in the decimal expansion of Pi.at n=13A083631
- a(0) = 1; a(n+1) = a(n)*2n + 2n + 1.at n=6A085644
- Sum of the prime(n) primes following prime(n).at n=16A099274
- Integers k such that k + phi(k) + phi(phi(k)) is a fourth power.at n=11A116041
- Nonprime numbers with all divisors starting and ending with digit 1.at n=14A208261
- Array read by upwards antidiagonals: A(n, k) = index of prime(k)^n in A098550.at n=32A253609
- a(n) = r*a(ceiling(n/2))+s*a(floor(n/2)) with a(1)=1 and (r,s)=(4,1).at n=42A268527
- Number A(n,k) of up-down sequences with k copies each of 1,2,...,n; square array A(n,k), n>=0, k>=0, read by antidiagonals.at n=40A275784
- Composite numbers k with its divisors having the property that the last digit of every divisor is the same as the first digit of the next divisor.at n=15A307858
- Number of even parts in the partitions of n into 10 parts.at n=39A309662
- a(n) is the number of quadruples (a_1, a_2, a_3, a_4) having all terms in {1,...,n} such that there exists a quadrilateral with these side lengths.at n=11A346636
- Triangle read by rows: T(n, k) = n! * 3^k * hypergeom([-k], [-n], 1/3).at n=19A375447
- Sorted positions of first appearances in A057820, the sequence of first differences of prime-powers.at n=42A376340