9131
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 9552
- Proper Divisor Sum (Aliquot Sum)
- 421
- 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
- 8712
- Möbius Function
- 1
- Radical
- 9131
- 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
- 153
- 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
- Divisors of 2^44 - 1.at n=23A003549
- Fermat pseudoprimes to base 4.at n=43A020136
- Pseudoprimes to base 31.at n=35A020159
- Strong pseudoprimes to base 16.at n=34A020242
- Strong pseudoprimes to base 31.at n=7A020257
- Number of days in n years (n=4 is the first leap year).at n=24A033171
- Number of days in n years (n=3 is the first leap year).at n=24A033172
- Number of days in n years (n=2 is the first leap year).at n=24A033173
- Number of partitions in parts not of the form 19k, 19k+1 or 19k-1. Also number of partitions with no part of size 1 and differences between parts at distance 8 are greater than 1.at n=42A035970
- Number of points in N^n of norm <= 2.at n=22A055417
- Number of 3-dimensional polyominoes (or polycubes) with n cells and rotational symmetry group of order exactly 4.at n=21A066281
- Pseudoquadprimes: p+4 for primes p where p+4 divides p^(p+4) + 4 and p+4 is composite.at n=7A100875
- Index of first occurrence of n-th prime in A001203, the continued fraction for Pi.at n=22A107892
- Semiprimes in A056108.at n=16A113527
- Start with 1013 and repeatedly reverse the digits and add 2 to get the next term.at n=18A120214
- a(1) = 1; a(n) = max{ 5*a(k) + a(n-k) | 1 <= k <= n/2 } for n > 1.at n=42A130667
- Number of 7 X 7 arrays of squares of integers, symmetric about both diagonal and antidiagonal, with all rows summing to n.at n=16A156392
- Number of n X n arrays of squares of integers, symmetric about both diagonal and antidiagonal, with all rows summing to 16.at n=6A156464
- Numbers k such that 2^(2k-1) == 2 (mod 2k) and such that 2^(k-1) != 1 (mod k).at n=21A176033
- Start with 3. If a, b in sequence, so is ab+1.at n=37A180432