1019
domain: N
Properties
Digital Properties
- Digit Count
- 4
- 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
- 1020
- 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
- 1018
- Möbius Function
- -1
- Radical
- 1019
- 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
- 62
- 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
- yes
- Safe Prime
- yes
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 171
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes p == 7, 19, 23 (mod 40) such that (p-1)/2 is also prime.at n=12A000353
- Lesser of twin primes.at n=35A001359
- Sum of Fibonacci (A000045) and Pell (A000129) numbers.at n=9A001932
- Smallest prime p==3 (mod 8) such that Q(sqrt(-p)) has class number 2n+1.at n=6A002148
- a(n) = 3^n reduced modulo 2^n.at n=11A002380
- Lucasian primes: p == 3 (mod 4) with 2*p+1 prime.at n=19A002515
- Primes p with a Fibonacci primitive root g, i.e., such that g^2 = g + 1 (mod p).at n=46A003147
- a(n) = a(n-1) + 2*a(n-3).at n=13A003476
- Erroneous version of A028491.at n=6A004060
- Divisible only by primes congruent to 4 mod 5.at n=43A004618
- Divisible only by primes congruent to 4 mod 7.at n=30A004622
- Class 4- primes (for definition see A005109).at n=23A005112
- Primes p such that 1 + product of primes up to p is prime.at n=7A005234
- Number of graphs on n nodes with 3 cliques.at n=11A005289
- Sophie Germain primes p: 2p+1 is also prime.at n=38A005384
- Safe primes p: (p-1)/2 is also prime.at n=25A005385
- Spiral sieve using Fibonacci numbers.at n=14A005620
- Odd numbers not of form p + 2^k (de Polignac numbers).at n=18A006285
- Worst cases for Pierce expansions (denominators).at n=16A006538
- Primes == 3 (mod 8).at n=44A007520