11945
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
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 14340
- Proper Divisor Sum (Aliquot Sum)
- 2395
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9552
- Möbius Function
- 1
- Radical
- 11945
- 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
- 249
- 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 whose product of digits is 9 times their sum.at n=36A062041
- Number of necklaces with n beads over an n-ary alphabet {a1,a2,...,an} such that #(w,a1) >= #(w,a2) >= ... >= #(w,ak) >= 0, where #(w,x) counts the letters x in word w.at n=8A072605
- Least positive integer solution k to h(k) = n h(k-1), where h(n) is the length of n, f(n), f(f(n)), ...., 1 in the Collatz (or 3x + 1) problem. (The earliest "1" is meant.)at n=9A078421
- Number of base 15 n-digit numbers with adjacent digits differing by five or less.at n=4A126536
- a(n) = gcd(a(n-1),n-1)*a(n-1) + d(n-1) if a(n-1) is not divisible by 2, otherwise a(n) = a(n-1)/2, where gcd denotes common divisor, d(n) is number of divisors of n.at n=48A133904
- Sum of even products minus sum of odd products of different pairs of numbers from 1 to n.at n=19A134449
- Expansion of x/((1-x-x^3)*(1-x)^6).at n=11A144900
- Number of crossings in a regular drawing of the complete bipartite graph K(n,n).at n=17A159065
- Number of decompositions of highly composite numbers (A002182) into unordered sums of two primes.at n=37A228943
- Numbers n such that n!!! - 3^4 is prime.at n=39A247464
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 453", based on the 5-celled von Neumann neighborhood.at n=25A272275
- The number of partitions of n which represent Chomp positions with Sprague-Grundy value 6.at n=54A284693
- Ranks of {2,3}-power towers with neither consecutive 2's nor consecutive 3's; see Comments.at n=24A299322
- a(n) is the number of 2-point antichains in the poset D_{2n+1} of type D, whose elements are compositions of 2n+1.at n=18A344791