9221
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 9222
- Proper Divisor Sum (Aliquot Sum)
- 1
- 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
- 9220
- Möbius Function
- -1
- Radical
- 9221
- 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
- 109
- 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
- yes
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 1143
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Number of n-covers of an unlabeled 3-set.at n=11A005745
- Numbers n such that n, 2n+1, and 4n+3 all prime.at n=40A007700
- Numbers k such that the continued fraction for sqrt(k) has period 31.at n=32A020370
- Primes that remain prime through 3 iterations of function f(x) = 4x + 3.at n=25A023281
- Primes with first digit 9.at n=40A045715
- Number of partitions of n with equal number of even and odd parts.at n=48A045931
- Primes p from A031924 such that A052180(p) = 23.at n=10A052238
- Primes of the form k^2 + 5.at n=7A056905
- Primes p such that p^12 reversed is also prime.at n=25A059705
- Initial primes of Cunningham chains of first type with length exactly 3. Primes in A059453 that survive as primes just two "2p+1 iterations", forming chains of exactly 3 terms.at n=22A059762
- Numbers k such that k*2^m-1 are composites for all exponents m in the range 0<=m<=k.at n=24A061154
- Primes p such that p-5 == 0 (mod phi(p-5)).at n=30A067557
- Least k such that gcd(prime(k+1)-1, prime(k)-1) = 2n.at n=24A067605
- Primes with either no internal digits or all internal digits are 2.at n=49A069677
- Fourth row of the Pascal-(1,4,1) array A081579.at n=8A081588
- Primes in which the unit place digit is 1 and the k-th most significant digit is prime (2,3,5,7) if k is prime else is composite (4,6,8,9,0).at n=21A089704
- Irregular primes whose indices are irregular primes of order one.at n=24A090869
- Smallest prime that begins with the digit reversal of prime(n).at n=49A093487
- a(n) = A000040(A096480(n)).at n=24A096481
- a(n) = (n-2) * 2^(n-1) + 5.at n=11A098821