8921
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 9744
- Proper Divisor Sum (Aliquot Sum)
- 823
- 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
- 8100
- Möbius Function
- 1
- Radical
- 8921
- 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
- 140
- 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
- Smallest nonnegative number that is the sum of 3 squares in exactly n ways.at n=41A000437
- Numbers that are the sum of 3 nonzero 6th powers.at n=18A003359
- Numbers that are the sum of at most 3 nonzero 6th powers.at n=33A004854
- Positive integers n such that 2^n == 2^11 (mod n).at n=77A015935
- Numbers k such that the continued fraction for sqrt(k) has period 72.at n=36A020411
- Self-convolution of natural numbers >= 3.at n=32A023551
- a(n) is the smallest number that is the sum of 3 nonzero squares in exactly n ways.at n=41A025414
- Composite numbers whose prime factors contain no digits other than 1 and 8.at n=3A036308
- Positive numbers having the same set of digits in base 8 and base 9.at n=38A037441
- Numbers k such that x^k + x^6 + 1 is irreducible over GF(2).at n=14A057476
- Reflective numbers: k such that the decimal encoding of the prime factorization of k (A067599) is palindromic.at n=41A066985
- a(n) = 2^(n-1) + (2 + (-1)^n)^((n-2)/2).at n=13A085613
- Least positive number having exactly n partitions into three squares.at n=41A095809
- Number of unordered pairs of partitions of n (into distinct parts) with empty intersection.at n=29A108796
- Least integer that can be written as a sum of 3 squares in n nontrivial ways (ignoring order and signs).at n=42A122699
- Smallest positive integer which can be expressed as the ordered sum of 3 squares in exactly n different ways.at n=42A124970
- First subdiagonal of triangular array T: T(j,1) = 1 for ((j-1) mod 6) < 3, else 0; T(j,k) = T(j-1,k-1) + T(j-1,k) for 2 <= k <= j.at n=14A131023
- Antidiagonal sums of triangular array T: T(j,1) = 1 for ((j-1) mod 6) < 3, else 0; T(j,k) = T(j-1,k-1) + T(j-1,k) for 2 <= k <= j.at n=26A131025
- Number of extreme n-breakable vectors.at n=23A141348
- Semiprimes whose factors are decimal palindromes when concatenated, omitting multiples of primes less than 11.at n=23A144719