9861
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 24
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 13920
- Proper Divisor Sum (Aliquot Sum)
- 4059
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6192
- Möbius Function
- -1
- Radical
- 9861
- 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
- 73
- Smith Number
- yes
- 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
- 4-dimensional analog of centered polygonal numbers: a(n) = n(n+1)*(n^2+n+4)/12.at n=18A006007
- 12-gonal (or dodecagonal) pyramidal numbers: a(n) = n*(n+1)*(10*n-7)/6.at n=18A007587
- a(n) = T(n,1) + T(n-1,2) + ...+ T(n-k+1,k), where k = floor((n+1)/2) and T is the array defined in A026098.at n=36A026103
- Number of days in n years (n=4 is the first leap year).at n=26A033171
- Number of partitions satisfying cn(1,5) <= cn(0,5) + cn(2,5) and cn(1,5) <= cn(0,5) + cn(3,5) and cn(4,5) <= cn(0,5) + cn(2,5) and cn(4,5) <= cn(0,5) + cn(3,5).at n=39A039874
- Smallest value of x such that M(x) = -n, where M(x) is Mertens's function A002321.at n=42A051401
- Inverse Mertens function: smallest k such that |M(k)| = n, where M(x) is Mertens's function A002321.at n=42A051402
- Number of partitions of n where n divides the product of the parts.at n=43A057568
- An inverse to Mertens's function: smallest k >= 2 such that Mertens's function |M(k)| (see A002321) is equal to n.at n=43A060434
- a(n) = A064842(n)/2.at n=38A064843
- Product of n-th prime number and n-th composite number.at n=39A067563
- An interleaved sequence of pyramidal and polygonal numbers.at n=35A081283
- a(n) = Sum_{i=1..n} 2^(b(i) - 1), where b(n) is the differences between consecutive primes.at n=43A086769
- Number of configurations of Sam Loyd's sliding block 15-puzzle that require a minimum of n moves to be reached, starting with the empty square at one of the 8 non-corner boundary squares.at n=12A090165
- Number of base 19 n-digit numbers with adjacent digits differing by two or less.at n=5A126406
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (-1, 1, 0), (0, 0, -1), (1, 0, -1), (1, 1, 0)}.at n=9A148683
- Sum of distances of numbers between successive powers of 2 (beginning with 2^1) to previous numbers with same number of prime factors, repetitions included. See example.at n=9A176883
- a(n) = 12*n^2 - 8*n + 1.at n=29A185212
- Calendar Problem #27, April 2012 Mathematics Teacher.at n=0A208646
- a(n) = n^4/8 + (5*n^3)/12 - n^2/8 - (5*n)/12 + 1.at n=17A226639