1847
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
- 2
- Divisor Sum
- 1848
- Proper Divisor Sum (Aliquot Sum)
- 1
- 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
- 1846
- Möbius Function
- -1
- Radical
- 1847
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 68
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 283
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes with 5 as smallest primitive root.at n=39A001124
- Smallest prime p such that there is a gap of 2n between p and previous prime.at n=7A001632
- Smallest prime == 7 (mod 8) where Q(sqrt(-p)) has class number 2n+1.at n=21A002146
- Primes of the form k^2 + k + 41.at n=40A005846
- Diagonals of Pascal's triangle mod 2 interpreted as binary numbers.at n=20A006921
- Number of non-Abelian metacyclic groups of order 2^n.at n=39A007982
- Coordination sequence T3 for Zeolite Code DAC.at n=27A008069
- Expansion of (1+x^11)/((1-x)*(1-x^2)*(1-x^3)*(1-x^4)).at n=51A008772
- a(n) = n^2 - 2.at n=42A008865
- Nine iterations of Reverse and Add are needed to reach a palindrome.at n=5A015990
- Megaperfect numbers: numbers n where A019294(n) = min {m: n divides sigma^(m) (n)} increases to a record; sigma^(m) means apply the sum-of-divisors function m times.at n=23A019276
- Number of 2's in n-th term of A007651.at n=30A022467
- Lonely (or isolated) primes: increasing distance to nearest prime.at n=5A023186
- Lonely (or isolated) primes: least prime of distance n from nearest prime (n = 1 or even).at n=7A023188
- Primes that remain prime through 2 iterations of the function f(x) = 5x + 4.at n=20A023253
- Primes that remain prime through 2 iterations of function f(x) = 6x + 1.at n=22A023256
- Primes that remain prime through 3 iterations of function f(x) = 5x + 4.at n=6A023284
- Greatest prime divisor of prime(n)*prime(n-1) + 1.at n=23A023525
- Least odd prime divisor of p(n)*p(n-1) + 1, or 1 if p(n)*p(n-1) + 1 is a power of 2.at n=23A023527
- a(n) = [ C(2n,n)/n^2 ].at n=9A024500