1807
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 1960
- Proper Divisor Sum (Aliquot Sum)
- 153
- 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
- 1656
- Möbius Function
- 1
- Radical
- 1807
- 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
- 117
- 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
- Sylvester's sequence: a(n+1) = a(n)^2 - a(n) + 1, with a(0) = 2.at n=4A000058
- Flavius Josephus's sieve: Start with the natural numbers; at the k-th sieving step, remove every (k+1)-st term of the sequence remaining after the (k-1)-st sieving step; iterate.at n=47A000960
- a(n) = least m such that if a/b < c/d where a,b,c,d are integers in [0,n], then a/b < k/m < c/d for some integer k.at n=48A001000
- Central polygonal numbers: a(n) = n^2 - n + 1.at n=43A002061
- Quadrinomial coefficients: C(2+n,n) + C(3+n,n) + C(4+n,n).at n=11A005718
- Least k such that binomial(k,n) has n or more distinct prime factors.at n=39A005733
- Number of interval graphs on n unlabeled nodes.at n=7A005975
- Odd numbers not of form p + 2^k (de Polignac numbers).at n=39A006285
- Denominators of worst case for Engel expansion.at n=26A006540
- Coordination sequence T1 for Zeolite Code MTT.at n=26A008189
- Coordination sequence T4 for Zeolite Code CON.at n=30A009871
- Coordination sequence T6 for Zeolite Code CON.at n=30A009873
- Coordination sequence T4 for Zeolite Code RUT.at n=28A009900
- a(0) = 1, a(n) = 5*n^2 + 2 for n>0.at n=19A010001
- a(n) = floor( n*(n-1)*(n-2)/28 ).at n=38A011910
- Pseudoprimes to base 42.at n=11A020170
- Pseudoprimes to base 43.at n=29A020171
- Strong pseudoprimes to base 42.at n=5A020268
- Strong pseudoprimes to base 43.at n=5A020269
- Numbers k such that the continued fraction for sqrt(k) has period 28.at n=30A020367