17021
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 11
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 17022
- Proper Divisor Sum (Aliquot Sum)
- 1
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 17020
- Möbius Function
- -1
- Radical
- 17021
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- 203
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 1962
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- T(n, 2*n-4), T given by A027960.at n=23A027966
- Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 23.at n=5A031611
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 66 ones.at n=29A031834
- Primes p from A031924 such that A052180(primepi(p)) = 29.at n=10A052236
- a(n) is the n-th prime whose decimal expansion begins with the decimal expansion of n.at n=16A077345
- Initial term in sequence of four consecutive primes separated by 3 consecutive differences each <=6 (i.e., when d = 2, 4 or 6) and forming d-pattern=[6,2,4]; short d-string notation of pattern = [624].at n=8A078853
- Third row of Pascal-(1,4,1) array A081579.at n=37A081587
- Numbers k such that k, sigma(k) and phi(k) have the same decimal digits (ignoring multiplicity).at n=21A082059
- Primes of the form p = prime(k+1) such that prime(k) = (prime(k+3)+prime(k-1))/2.at n=16A126239
- Antidiagonal sums of triangular array T: T(j,1) = 1 for ((j-1) mod 8) < 4, else 0; T(j,k) = T(j-1,k-1) + T(j,k-1) for 2 <= k <= j.at n=28A131077
- Number of primitive multiplex juggling sequences of length n, base state <2,1> and hand capacity 3.at n=6A136786
- Primes p such that p^3 +- (p+1) are primes.at n=22A137472
- Primes of the form 210n+11.at n=39A140840
- Primes congruent to 7 mod 47.at n=41A142358
- Primes congruent to 8 mod 53.at n=40A142538
- Primes congruent to 29 mod 59.at n=37A142756
- Primes congruent to 2 mod 61.at n=30A142800
- Primes of the form (4*n^2-8*n-9)/3.at n=31A154616
- Positive integers of the form (30*m^2+1)/11.at n=14A179339
- Cyclops emirps.at n=21A183057