15643
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 15644
- 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
- 15642
- Möbius Function
- -1
- Radical
- 15643
- 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
- 146
- 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
- 1824
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- a(1) = 2, a(n+1) = smallest prime of the form a(n) + k*prime(n+1), k >1.at n=33A085041
- a(n) = 8*n^2 + 88*n + 43.at n=39A086760
- a(1) = 3; for n > 1 a(n) is the least prime of form a(n-1) + k*prime(n-1) with k > 0.at n=34A095184
- Recurrence sequence based on positions of digits in decimal places of phi, the Golden Ratio = (1+sqrt(5))/2.at n=14A098324
- a(1)=1; a(n) = gcd(a(n-1), n) + lcm(a(n-1), n).at n=8A129090
- The upper twin prime whose lower member has a prime index.at n=36A129782
- Numbers whose base-10 and base-7 representations are permutations of the same multiset of digits.at n=31A130604
- Sum of third powers of five consecutive primes.at n=3A133539
- Prime quadruples: 2nd term.at n=13A136720
- Prime numbers p such that p +- ((p-1)/3) are primes.at n=15A137703
- Primes congruent to 39 mod 47.at n=40A142390
- Primes congruent to 12 mod 49.at n=40A142424
- Primes congruent to 8 mod 53.at n=36A142538
- Primes congruent to 8 mod 59.at n=30A142735
- Primes congruent to 27 mod 61.at n=28A142825
- Primes p such that the multiplicative order of 2 modulo p is (p-1)/9.at n=9A152309
- Primes congruent to 32 mod 67.at n=30A154621
- Primes that are the sum of cubes of 5 consecutive primes.at n=0A165612
- List of 4-tuples of twin primes q, p, p+2 and q+2 such that 3*q < 2*p < 2*(p+2) < 3*(q+2).at n=42A177433
- Smallest emirp corresponding to the prime of A178581.at n=21A178582