1939
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 2224
- Proper Divisor Sum (Aliquot Sum)
- 285
- 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
- 1656
- Möbius Function
- 1
- Radical
- 1939
- 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
- 50
- 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
- Number of series-reduced star graphs with n edges.at n=9A002935
- An upper bound on the biplanar crossing number of the complete graph on n nodes.at n=28A007333
- Coordination sequence T3 for Zeolite Code AEL.at n=29A008006
- Coordination sequence T3 for Zeolite Code DAC.at n=28A008069
- Coordination sequence T1 for Zeolite Code MEI.at n=32A008146
- Coordination sequence T5 for Zeolite Code NES.at n=28A008209
- Number of ordered triples of integers from [ 1,n ] with no common factors between pairs.at n=33A015632
- Smallest odd k>n such that k | n^k + n, or 0 if n=2^m.at n=35A015908
- Positive integers n such that 2^n == 2^7 (mod n).at n=48A015927
- Numbers k such that the continued fraction for sqrt(k) has period 34.at n=13A020373
- a(n) = a(n-1) + a(n-2) + 1, with a(0)=3, a(1)=10.at n=12A022409
- Coordination sequence T8 for Zeolite Code MWW.at n=29A024993
- a(1) = 7; a(n+1) = a(n)-th composite.at n=20A025011
- a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0, |s(i) - s(i-1)| = 1 for i = 1,2,3; |s(i) - s(i-1)| <= 1 for i >= 4, s(n) = 2. Also a(n) = T(n,n-2), where T is the array defined in A026082.at n=6A026085
- a(n) = T(n,0) + T(n,1) + ... + T(n,[ n/2 ]), T given by A026659.at n=11A026667
- Cube root of A030697.at n=8A030698
- Numbers whose base-10 representation has 2 fewer 0's than 9's.at n=35A031500
- Numbers k such that 231*2^k+1 is prime.at n=39A032492
- Coordination sequence T4 for Zeolite Code SBT.at n=35A033615
- a(1)=1, a(n) = smallest odd number such that all sums of pairs of (not necessarily distinct) terms in the sequence are distinct.at n=26A034757