13079
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 15120
- Proper Divisor Sum (Aliquot Sum)
- 2041
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 11200
- Möbius Function
- -1
- Radical
- 13079
- Omega Function (Ω)
- 3
- 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
- 169
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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) = Sum_{k=0..n} (k+1)*T(n, n-k), where T is given by A008288.at n=9A026937
- a(n) = Sum_{i=0..n} A047080(i,n-i).at n=23A047084
- Numbers k such that phi(sigma(phi(k))) = sigma(k).at n=7A066462
- Pell pseudoprimes: odd composite numbers n such that P(n)-Kronecker(2,n) is divisible by n.at n=21A099011
- a(n) + a(n+1) + a(n+2) = n^3.at n=35A152728
- a(n) = (6 + 10*n + 5*n^2 + n^3)/2.at n=28A164845
- A triangle with Pell numbers in the first column.at n=56A164981
- Partial sums of A061262.at n=27A176661
- Number of (n+2) X 7 0..1 arrays with every 3 X 3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally exactly three ways, and new values 0..1 introduced in row major order.at n=15A204378
- Numbers that can be written in more than 1 way as p^2 + 3pq + q^2 with primes p < q.at n=9A218795
- Numbers such that the sequence of all possible sums of divisors of n is increasing but not strictly so, the sums being ordered by their characteristic functions, seen as binary numbers (see example).at n=8A230492
- Numbers k such that (76*10^k + 167)/9 is prime.at n=23A275802
- a(n) = a(n-1) + 3*a(n-2) -2*a(n-3) - 2*a(n-4), where a(0) = -1, a(1) = -1, a(2) = -1, a(3) = 1.at n=18A295732
- a(n) = a(n-1) + 3*a(n-2) -2*a(n-3) - 2*a(n-4), where a(0) = 0, a(1) = 0, a(2) = -1, a(3) = 2.at n=20A295734
- Composite numbers k such that Pell(k) == 1 (mod k).at n=24A319042
- Odd composite integers m such that U(m)^2 == 1 (mod m) and V(m) == 5 (mod m), where U(m)=A004254(m) and V(m)=A003501(m) are the m-th generalized Lucas and Pell-Lucas numbers of parameters a=5 and b=1, respectively.at n=29A337779
- Products of three distinct strong primes.at n=6A363782
- Sphenic numbers k such that floor(log(k)/log(lpf(k))) = 1+floor(log(k)/log(p)) for all primes p | k such that p > lpf(k), where lpf = A020639(k).at n=28A383177