1928
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 3630
- Proper Divisor Sum (Aliquot Sum)
- 1702
- 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
- 960
- Möbius Function
- 0
- Radical
- 482
- Omega Function (Ω)
- 4
- 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
- 24
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- yes
- Odd
- no
Appears in sequences
- Number of distinct values taken by 2^2^...^2 (with n 2's and parentheses inserted in all possible ways).at n=12A002845
- Record values in A005210.at n=48A005211
- Number of nonsplit type 2 metacyclic 2-groups of order 2^n.at n=53A007981
- Coordination sequence T2 for Zeolite Code ERI.at n=32A008094
- Molien series for A_6.at n=33A008629
- a(n) = ceiling of Gamma(n + 2/9)/Gamma(2/9).at n=8A020113
- a(n) = n*(15*n + 1)/2.at n=16A022273
- Numbers k such that Fib(k) == 21 (mod k).at n=17A023179
- a(n) = (n + 3)^2 - 8.at n=41A028884
- a(n) = 2^n - n^2 + 1.at n=11A030110
- Numbers k such that the continued fraction for sqrt(k) has even period 2*m and the m-th term of the periodic part is 9.at n=23A031412
- Concatenation of n and n + 9 or {n,n+9}.at n=18A032614
- Numbers whose base-15 expansion has no run of digits with length < 2.at n=21A033028
- Coordination sequence T5 for Zeolite Code CFI.at n=29A033603
- Fractional part of square root of a(n) starts with 9: first term of runs.at n=38A034115
- Number of partitions of n into parts not of the form 13k, 13k+6 or 13k-6. Also number of partitions with at most 5 parts of size 1 and differences between parts at distance 5 are greater than 1.at n=28A035954
- Number of partitions satisfying (cn(0,5) <= cn(2,5) = cn(3,5) and cn(0,5) <= cn(1,5) and cn(0,5) <= cn(4,5)).at n=37A036807
- Denominators of continued fraction convergents to sqrt(694).at n=10A042335
- Base-5 palindromes that start with 3.at n=14A043008
- Numbers k such that 2 and 8 occur juxtaposed in the base-10 representation of k but not of k-1.at n=38A043238