1785
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 3456
- Proper Divisor Sum (Aliquot Sum)
- 1671
- 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
- 768
- Möbius Function
- 1
- Radical
- 1785
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 4
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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 29
- 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
- Square pyramidal numbers: a(n) = 0^2 + 1^2 + 2^2 + ... + n^2 = n*(n+1)*(2*n+1)/6.at n=17A000330
- Triangle of numbers related to triangle A049213; generalization of Stirling numbers of second kind A008277, Bessel triangle A001497.at n=11A000369
- A self-generating sequence: a(1)=1, a(2)=2, a(n+1) chosen so that a(n+1)-a(n-1) is the first number not obtainable as a(j)-a(i) for 1<=i<j<=n.at n=47A001149
- Total height of all rooted trees on n labeled nodes.at n=4A001854
- Odd squarefree numbers with an even number of prime factors that have no prime factors greater than 31.at n=48A002557
- Numbers that are the sum of 5 positive 5th powers.at n=34A003350
- Divisors of 2^24 - 1.at n=41A003532
- a(n) = floor(n*phi^8), where phi is the golden ratio, A001622.at n=38A004923
- a(n) = round(n*phi^8), where phi is the golden ratio, A001622.at n=38A004943
- Bond percolation series for mean cluster size on directed cubic lattice.at n=7A006810
- a(n) = binomial(n+3, 3)/4 for odd n, n*(n+2)*(n+4)/24 for even n.at n=33A006918
- a(n) = n*(4*n+1).at n=21A007742
- Coordination sequence T5 for Zeolite Code MTT.at n=26A008193
- Molien series of 4-dimensional representation of cyclic group of order 4 over GF(2) (not Cohen-Macaulay).at n=33A008610
- Dates of birth of Kings Louis I, II, ... of France.at n=16A008746
- a(n) = floor(n*(n-1)*(n-2)/24).at n=36A011842
- Nearest integer to (n/2)^4.at n=13A011863
- a(n) = floor( n*(n-1)*(n-2)/22 ).at n=35A011904
- a(n) = floor( n*(n-1)*(n-2)*(n-3)/32 ).at n=17A011942
- Orders of cyclotomic polynomials containing a coefficient the absolute value of which is >= 3.at n=15A013591