12405
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 19872
- Proper Divisor Sum (Aliquot Sum)
- 7467
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6608
- Möbius Function
- -1
- Radical
- 12405
- 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
- 156
- 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
- Coefficient of x^n in Product_{k>=1} 1/(1-x^k)^n.at n=7A008485
- Number of partitions of n into parts of 7 kinds.at n=7A023006
- Positive numbers k such that k and 3*k are anagrams in base 7 (written in base 7).at n=14A023069
- a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2) and t = A002808 (composite numbers).at n=44A023863
- Numbers having four 3's in base 6.at n=33A043384
- Numbers whose base-7 representation contains exactly four 1's.at n=28A043400
- Expansion of (1+2*x+3*x^2)/((1-x)^3*(1-x^2)).at n=28A055232
- Number of unlabeled and connected graphs which are complements of chordal graphs.at n=8A079456
- A card-arranging problem: number of permutations p_1, ..., p_n of 1, ..., n such that i + p_i is a square for every i.at n=32A095986
- G.f.: A(x) = x/(1-x) o x/(1-x^2) o x/(1-x^4) o x/(1-x^8) o..., composition of functions x/(1 - x^{2^n}) for n=0,1,2,3,...at n=17A136752
- Ulam's spiral (ENE spoke).at n=28A143856
- 5 times centered pentagonal numbers: 5*(5*n^2 + 5*n + 2)/2.at n=31A164015
- a(0) = 0 and a(n) = (4*n^3 - 12*n^2 + 20*n - 9)/3 for n >= 1.at n=22A174794
- Triangle read by rows: T(n,k) is the number of permutations of [n] having k fixed blocks.at n=39A180192
- Number of nondecreasing arrangements of 5 numbers x(i) in -(n+3)..(n+3) with the sum of sign(x(i))*x(i)^2 zero.at n=40A188005
- Number of n X 6 binary arrays without the pattern 1 1 0 diagonally, vertically, antidiagonally or horizontally.at n=2A188604
- T(n,k)=Number of nXk binary arrays without the pattern 1 1 0 diagonally, vertically, antidiagonally or horizontally.at n=30A188607
- Number of 3Xn binary arrays without the pattern 1 1 0 diagonally, vertically, antidiagonally or horizontally.at n=5A188608
- a(n) = 2^n * (n^4 - 4*n^3 + 18*n^2 - 52*n + 75) - 75.at n=5A209359
- Number of idempotent n X n 0..1 matrices of rank n-2.at n=5A224117