16321
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 17200
- Proper Divisor Sum (Aliquot Sum)
- 879
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 15444
- Möbius Function
- 1
- Radical
- 16321
- 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
- 66
- 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
- From a Goldbach conjecture: the location of records in A185091.at n=13A002091
- a(n) = position of 3*n^3 in A003072.at n=36A024970
- Numbers k such that 219*2^k+1 is prime.at n=34A032486
- Numbers whose base-5 representation has exactly 7 runs.at n=29A043607
- a(n) = sum of the first n upper twin primes.at n=38A086168
- Negative numbers written in a bits-of-Pi/primorial base system.at n=16A109839
- Semiprimes in A054556.at n=18A113693
- Sequence with a (1,-1) Somos-4 Hankel transform.at n=13A178080
- Odd numbers n>5 in the representation n=2*p+q, p, q prime, q minimal, at which a larger q than for any smaller n is needed. A194829 gives values of q.at n=14A194828
- Numbers n such that Q(sqrt(n)) has class number 9.at n=26A218041
- Fundamental discriminants of real quadratic number fields with class number 9.at n=16A218159
- Expansion of -(4*x^3+8*x^2+4*x+1)/(2*x^4+4*x^3+2*x^2-x-1).at n=16A270307
- Number of compositions of n if only the order of the even numbers matter.at n=26A275592
- Odd composite integers m such that U(m)^2 == 1 (mod m) and V(m) == 6 (mod m), where U(m) and V(m) are the m-th generalized Lucas and Pell-Lucas numbers of parameters a=6 and b=-1, respectively.at n=19A337629
- Odd composite integers m such that A085447(m) == 6 (mod m).at n=26A338078
- Total number of levels in all Dyck paths of semilength n containing exactly 2 path nodes.at n=10A371903
- T(n,k) is the total number of levels in all Dyck paths of semilength n containing exactly k path nodes; triangle T(n,k), n>=0, 1<=k<=n+1, read by rows.at n=56A371928