1619
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 1620
- 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
- 1618
- Möbius Function
- -1
- Radical
- 1619
- 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
- 47
- 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
- yes
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 256
- 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=15A000353
- A jumping problem.at n=14A002466
- Class 4- primes (for definition see A005109).at n=40A005112
- Safe primes p: (p-1)/2 is also prime.at n=34A005385
- Odd numbers not of form p + 2^k (de Polignac numbers).at n=32A006285
- Coordination sequence T1 for Zeolite Code TON.at n=25A008241
- Coordination sequence T4 for Zeolite Code RSN.at n=26A009888
- a(n) = prime(n^2).at n=15A011757
- Six iterations of Reverse and Add are needed to reach a palindrome.at n=28A015984
- Primes that are palindromic in base 2 (but written here in base 10).at n=14A016041
- Powers of fifth root of 14 rounded to nearest integer.at n=14A018154
- Powers of fifth root of 14 rounded up.at n=14A018155
- Numbers k such that the continued fraction for sqrt(k) has period 42.at n=8A020381
- Smallest nonempty set S containing prime divisors of 9k+8 for each k in S.at n=46A020630
- Primes of the form 36*n^2 - 810*n + 2753, n >= 0, sorted.at n=5A022464
- a(n) = [ a(n-1)/a(1) + a(n-2)/a(2) + ... + a(1)/a(n-1) ], for n >= 3.at n=16A022863
- Numbers k such that k and 8*k + 1 are both prime.at n=46A023228
- a(n) = b(n) + d(n), where b(n) = (n-th Fibonacci number > 1) and d(n) = (n-th non-Fibonacci number).at n=14A023483
- n-th non-Lucas number plus Fibonacci(n + 1).at n=15A023490
- Numbers with exactly 5 2's in their ternary expansion.at n=25A023703