5851
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 5852
- 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
- 5850
- Möbius Function
- -1
- Radical
- 5851
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 142
- 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
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 769
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Indices of prime Lucas numbers.at n=30A001606
- Primes of the form k^2 - k - 1.at n=40A002327
- a(n) = 1 + n/2 + 9*n^2/2.at n=36A006137
- Numbers k such that the continued fraction for sqrt(k) has period 94.at n=6A020433
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 75.at n=24A031573
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 40 ones.at n=23A031808
- Lucky numbers with size of gaps equal to 18 (lower terms).at n=31A031900
- Base-2 digits of a(n) are, in order, the first n terms of the periodic sequence with initial period 1,0,1.at n=12A033120
- Numbers whose maximal base-8 run length is 4.at n=16A037995
- Primes p such that both p-2 and 2p-1 are prime.at n=36A038869
- Denominators of continued fraction convergents to sqrt(237).at n=8A041443
- Denominators of continued fraction convergents to sqrt(948).at n=8A042835
- (s(n)+1)/9, where s(n)=n-th base 9 palindrome that starts with 8.at n=22A043079
- Numbers having four 3's in base 8.at n=1A043436
- Discriminants of imaginary quadratic fields with class number 21 (negated).at n=16A046018
- a(n) = T(2n-1,n), array T given by A048201.at n=38A048208
- Primes whose consecutive digits differ by 3 or 4.at n=20A048415
- Primes p such that p and p^2 have same digit sum.at n=12A058370
- Numbers k such that floor(phi^k) is prime, where phi is the golden ratio.at n=30A059791
- Partial sums of sequence (essentially A002378): 1, 2, 6, 12, 20, 30, 42, 56, 72, 90, ...at n=25A064999