9421
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 9422
- 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
- 9420
- Möbius Function
- -1
- Radical
- 9421
- 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
- 34
- 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
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 1166
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- From table of maximal epacts e(p) and corresponding primes p, for x_1=2, x_{m+1} = (x_m)^2+1; sequence gives p.at n=28A014424
- Expansion of Product_{m>=1} (1 + q^m)^m; number of partitions of n into distinct parts, where n different parts of size n are available.at n=18A026007
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 54 ones.at n=26A031822
- Decimal part of a(n)^(1/3) starts with reversal of its integer part: first term of runs.at n=19A034309
- Number of partitions of n with equal number of parts congruent to each of 0, 3 and 4 (mod 5).at n=50A035577
- Primes with distinct digits in descending order.at n=46A052014
- Run through primes p; if the digits of p*q (where q is the prime following p) can be rearranged to form one or more primes r, append these primes r to the sequence.at n=25A053736
- Number of nonisomorphic cyclic subgroups of the group S_n X S_n (where S_n is the symmetric group of degree n).at n=46A063183
- Twin primes belonging to packs of four or more twin pairs.at n=1A068220
- Successive left concatenation of floor(k/2) beginning with n until we reach 1.at n=8A068657
- Primes in A068657.at n=4A068658
- Twin primes belonging to packs of three or more twin pairs.at n=38A069467
- a(n)=60*sum(1<=i<=j<=k<=n,i^2*j/k).at n=5A088942
- Primes p such that (p-11)/10 is also a prime.at n=40A089442
- Upper bound of twin prime pairs whose digital reverse is prime.at n=39A101782
- a(n) = 1 + 2 * least i such that A103507(i)=n+1, 0 if no such i exists.at n=23A103508
- Lesser prime in pair prime(k) +/- k for some k.at n=20A107636
- Primes such that the sum of the predecessor and successor primes is divisible by 29.at n=35A112859
- Numbers n such that p(5n) is prime, where p(n) is the number of partitions of n.at n=26A114166
- Primes produced by a pyramidal ( three variable sequence) that is based on the Euler totient and multiperfect sigma functions.at n=23A117843