7919
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 26
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 7920
- 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
- 7918
- Möbius Function
- -1
- Radical
- 7919
- 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
- 75
- 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
- 1000
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- a(n) = (10^n)-th prime.at n=3A006988
- 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=27A014424
- Primes that are palindromic in base 2 (but written here in base 10).at n=28A016041
- Ceiling of Gamma(n+1/2)/Gamma(1/2).at n=8A020135
- Primes of the form k^2 - 2.at n=24A028871
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 87.at n=33A031585
- a(n) = prime(100*n).at n=9A031921
- a(n) = prime(1000 * n).at n=0A031922
- Largest sequence of primes obtained by adding two-distinct-digit primes, growing from left to right.at n=1A032910
- Numbers k such that p-k=p#-k#, where p=nextprime(k), k#=nextprime(square root of k), p#=nextprime(square root of p).at n=2A037210
- Denominators of continued fraction convergents to sqrt(213).at n=10A041397
- Numbers whose base-4 representation contains exactly two 2's and four 3's.at n=21A045147
- a(n) = prime(n)^2 - 2.at n=23A049001
- Primes of form p^2 - 2, where p is prime.at n=12A049002
- Numbers k such that 275*2^k + 1 is prime.at n=22A053354
- Primes p such that a pure prime power occurs between p and the next prime.at n=44A053607
- Primes p of form q^k-2 where q is also a prime and k > 1.at n=17A053705
- Largest prime below prime(n)^2 (A001248).at n=23A054270
- Second term of strong prime 5-tuples: p(m)-p(m-1) > p(m+1)-p(m) > p(m+2)-p(m+1) > p(m+3)-p(m+2).at n=22A054809
- a(0)=1, a(n) = prime(n^3).at n=10A055875