6851
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
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 8064
- Proper Divisor Sum (Aliquot Sum)
- 1213
- 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
- 5760
- Möbius Function
- -1
- Radical
- 6851
- 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
- 57
- 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
- a(n) = floor(binomial(n,4)/4).at n=30A011850
- Positive integers n such that 2^n == 2^11 (mod n).at n=66A015935
- Product of prime p with sum of next p consecutive primes.at n=5A036660
- Gaps of 7 in sequence A038593 (lower terms).at n=22A038653
- Numbers ending with '1' that are the difference of two positive cubes.at n=28A038856
- Base-6 palindromes that start with 5.at n=24A043014
- Composite numbers k such that k!/k# + 1 is prime, where k# = primorial numbers A034386.at n=20A049420
- 23-gonal numbers: a(n) = n(21n-19)/2.at n=26A051875
- Truncated triangular pyramid numbers: a(n) = Sum_{k=4..n} (k*(k+1)/2 - 9).at n=30A051937
- Numbers k such that phi(k)+sigma(k) is a perfect cube.at n=7A061366
- Numbers n such that n and its reversal are both multiples of 13.at n=32A062903
- Non-palindromic number and its reversal are both multiples of 13.at n=19A062912
- Numbers k such that 2^k + Fibonacci(k) is prime.at n=18A074824
- Number of permutations satisfying -k<=p(i)-i<=r and p(i)-i not in I, i=1..n, with k=3, r=3, I={-1,1}.at n=13A079991
- Largest proper divisor of the n-th Carmichael number (A002997).at n=15A081703
- Natural numbers of the form p^3 - q^3, where p and q are primes.at n=29A086120
- Numbers n such that n and n+1 both are members of A074997; i.e., on the one hand n-1 and n+1 have the same prime signature, on the other hand n and n+2 have the same prime signature.at n=40A086540
- n*(1+3*n+6*n^2)/2.at n=13A115519
- Positions of high-water marks of A118421.at n=42A118423
- Numerator of sum of reciprocals of first n 5-simplex numbers A000389.at n=25A118431