1801
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 10
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 1802
- 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
- 1800
- Möbius Function
- -1
- Radical
- 1801
- 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
- 161
- 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
- 279
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- A sequence of sorted odd primes 3 = p_1 < p_2 < ... < p_m such that p_i-2 divides the product p_1*p_2*...*p_(i-1) of the earlier primes and each prime factor of p_i-1 is a prime factor of twice the product.at n=14A001259
- From a Goldbach conjecture: records in A185091.at n=24A002092
- Primes of the form 2^q*3^r*5^s + 1.at n=40A002200
- Cuban primes: primes which are the difference of two consecutive cubes.at n=12A002407
- a(n) = largest noncomposite factor of 2^(2n+1) - 1.at n=12A002588
- Sextan primes: p = (x^6 + y^6)/(x^2 + y^2).at n=8A002647
- Hex (or centered hexagonal) numbers: 3*n*(n+1)+1 (crystal ball sequence for hexagonal lattice).at n=24A003215
- Divisors of 2^25 - 1.at n=3A003533
- Divisors of 2^50 - 1.at n=11A003554
- Triangular numbers written backwards.at n=46A004158
- Largest prime factor of 2^n - 1.at n=23A005420
- a(n) = 1 + a(floor(n/2))*a(ceiling(n/2)).at n=18A005468
- x^3 + n*y^3 = 1 is solvable.at n=39A005988
- Primes of form x^3 + y^3 + z^3 where x,y,z > 0.at n=42A007490
- Primes p == 1 (mod 8), p = a^2 + 64*b^2 such that y^2 = x^3 + p*x has rank 2.at n=24A007766
- Coordination sequence T4 for Zeolite Code AFO.at n=28A008018
- Coordination sequence T2 for Zeolite Code AFT.at n=32A008027
- Coordination sequence T1 for Zeolite Code GME and AFX.at n=32A008110
- Coordination sequence T2 for Zeolite Code PAU.at n=31A008220
- Number of partitions of n into at most 8 parts.at n=28A008637