1641
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 2192
- Proper Divisor Sum (Aliquot Sum)
- 551
- 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
- 1092
- Möbius Function
- 1
- Radical
- 1641
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- 73
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
- a(n) = least m such that if a/b < c/d where a,b,c,d are integers in [0,n], then a/b < k/m < c/d for some integer k.at n=46A001000
- Central polygonal numbers: a(n) = n^2 - n + 1.at n=41A002061
- a(1) = 0, a(2) = -2; for n > 2, a(n) + a(n-2) - a(n-3) - a(n-5) - ... - a(n-p) = (-1)^(n+1)*n if n is prime, otherwise = 0, where p = largest prime < n.at n=38A002120
- Expansion of 1/((1-x)^3*(1-x^2)^2*(1-x^3)).at n=14A002625
- Number of solutions to a linear inequality.at n=36A002797
- Numbers k such that k, k+1 and k+2 have the same number of divisors.at n=29A005238
- Number of n-step spirals on hexagonal lattice.at n=11A006778
- Coordination sequence T1 for Zeolite Code LEV.at n=30A008127
- Coordination sequence T1 for Zeolite Code LTA and RHO.at n=32A008137
- Molien series of 4-dimensional representation of cyclic group of order 4 over GF(2) (not Cohen-Macaulay).at n=32A008610
- Coordination sequence T1 for Zeolite Code WEI.at n=29A009917
- Expansion of 1/(1-x^5-x^6-x^7-x^8-x^9).at n=39A017840
- Powers of fifth root of 5 rounded down.at n=23A018126
- Numbers k such that Fibonacci(k) == -2 (mod k).at n=25A023163
- a(n) = position of 5 + n^2 in A004432.at n=43A024808
- Least m such that if r and s in {Pi/2 - atn(h): h = 1,2,...,n} satisfy r < s, then r < k/m < s for some integer k.at n=45A024832
- a(n) = least m such that if r and s in {1/1, 1/3, 1/5, ..., 1/(2n-1)} satisfy r < s, then r < k/m < (k+1)/m < s for some integer k.at n=22A024834
- a(n) = Sum_{k=2..n} k*floor(n/k).at n=43A024917
- Numbers that are the sum of 3 distinct nonzero squares in exactly 10 ways.at n=37A025348
- Least k>1 such that complement of first n terms of A006928 repeats beginning at k-th term.at n=57A025510