1855
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
- 8
- Divisor Sum
- 2592
- Proper Divisor Sum (Aliquot Sum)
- 737
- 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
- 1248
- Möbius Function
- -1
- Radical
- 1855
- 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
- 117
- 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
- Rencontres numbers: number of permutations of [n] with exactly one fixed point.at n=6A000240
- Number of permutations of length n with 3 consecutive ascending pairs.at n=7A000313
- Expansion of 1/(1-x)^2/(1-x^2)/(1-x^4)/(1-x^10)/(1-x^20).at n=34A001307
- Number of series-reduced planted trees with n+9 nodes and 4 internal nodes.at n=15A001860
- Numbers k such that 33*2^k - 1 is prime.at n=26A002240
- Second pentagonal numbers: a(n) = n*(3*n + 1)/2.at n=35A005449
- Number of partitions of n into Fibonacci parts (with 2 types of 1).at n=25A007000
- Number of nodes in regular n-gon with all diagonals drawn.at n=17A007569
- Coordination sequence T1 for Zeolite Code DDR.at n=27A008071
- Coordination sequence T3 for Zeolite Code MTW.at n=28A008198
- Triangle T(n,k) of rencontres numbers (number of permutations of n elements with k fixed points).at n=29A008290
- Triangle of rencontres numbers.at n=16A008291
- Expansion of (1 + 2*x^2 + x^3)/((1 - x)^2*(1 - x^3)).at n=52A008822
- Coordination sequence T2 for Zeolite Code -CHI.at n=27A009847
- Triangle read by rows: T(n,k) is the number of permutations of [n] having k consecutive ascending pairs (0 <= k <= n-1).at n=32A010027
- Expansion of e.g.f. arcsin(sec(x)*arcsinh(x)) (odd powers only).at n=3A012823
- Orders of cyclotomic polynomials containing a coefficient the absolute value of which is >= 3.at n=16A013591
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly three 1's.at n=25A013650
- Powers of fifth root of 6 rounded to nearest integer.at n=21A018130
- Powers of fifth root of 6 rounded up.at n=21A018131