13045
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 15660
- Proper Divisor Sum (Aliquot Sum)
- 2615
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 10432
- Möbius Function
- 1
- Radical
- 13045
- 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
- 138
- 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
- Positive numbers having the same set of digits in base 7 and base 10.at n=39A037440
- a(0) = 1, a(1) = 5; for n >= 2 a(n) is the number of degree-n monic reducible polynomials over GF(5), i.e., a(n) = 5^n - A001692(n).at n=6A058820
- Numerator of the generalized harmonic number H(n,5,2).at n=4A075139
- Expansion of 1/(1 - 2*x - x^2 - 2*x^3).at n=10A077938
- Expansion of 1/(1+2*x-x^2+2*x^3).at n=10A077987
- Numbers whose base-10 and base-7 representations are permutations of the same multiset of digits.at n=26A130604
- a(1)=1. For m >= 0 and 1 <= k <= 2^m, a(2^m +k) = a(k) + Sum_{j=1..2^m} a(j).at n=44A139485
- Digit sums of A092571.at n=17A165724
- Where records occur in A169784.at n=40A175437
- Number of nX3 binary arrays without the pattern 0 0 0 antidiagonally or horizontally.at n=4A188868
- T(n,k)=Number of nXk binary arrays without the pattern 0 0 0 antidiagonally or horizontally.at n=25A188874
- Number of 5Xn binary arrays without the pattern 0 0 0 antidiagonally or horizontally.at n=2A188877
- T(n,k)=Number of nXk binary arrays without the pattern 0 1 0 antidiagonally or horizontally.at n=25A189064
- Number of 5Xn binary arrays without the pattern 0 1 0 antidiagonally or horizontally.at n=2A189067
- Number of nX5 binary arrays without the pattern 0 0 1 vertically or antidiagonally.at n=2A189192
- T(n,k)=Number of nXk binary arrays without the pattern 0 0 1 vertically or antidiagonally.at n=23A189196
- T(n,k)=Number of nXk 0..1 arrays with rows and antidiagonals unimodal.at n=25A223680
- Number of 5Xn 0..1 arrays with rows and antidiagonals unimodal.at n=2A223683
- Least number k such that k^n - k +/- 1 are twin primes, or 0 if no such k exists.at n=59A248082
- a(n) = (8*n+13*n^3+3*n^5)/24; also the sum of triangular numbers taken in successive groups of increasing size (see Example).at n=9A260513