1609
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
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 1610
- 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
- 1608
- Möbius Function
- -1
- Radical
- 1609
- 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
- 73
- 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
- 254
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes with 7 as smallest primitive root.at n=14A001126
- a(n) = floor(1000*log(n)).at n=4A004240
- a(n) = 1000*log(n) rounded to the nearest integer.at n=4A004241
- Divisible only by primes congruent to 6 mod 7.at n=46A004624
- a(n) = floor(n*phi^12), where phi is the golden ratio, A001622.at n=5A004927
- Class 4- primes (for definition see A005109).at n=39A005112
- Primes p such that 2p-1 is also prime.at n=45A005382
- Greater of twin primes.at n=50A006512
- Minimal absolute value of discriminants of number fields of degree n.at n=4A006557
- From the graph reconstruction problem.at n=8A006653
- Smallest odd number expressible in at least n ways as p+2*m^2 where p is 1 or a prime and m >= 0.at n=21A007697
- Primes p == 1 (mod 8), p = a^2 + 64*b^2 such that y^2 = x^3 + p*x has rank 2.at n=21A007766
- a(n) = n OR n^2 (applied to ternary expansions).at n=39A008467
- Primes p==1 (mod 6) such that 3 and -3 are both cubes (one implies other) modulo p.at n=38A014753
- Primes p == 1 mod 8 such that 2 and -2 are both 4th powers (one implies other) mod p.at n=27A014754
- Six iterations of Reverse and Add are needed to reach a palindrome.at n=27A015984
- Least k such that (2*p_n)*k + 1 | Mersenne(p_n), p_n = n-th prime, n >= 2.at n=18A016048
- Numbers k such that the continued fraction for sqrt(k) has period 57.at n=1A020396
- Let q_k = p*(p+2) be product of k-th pair of twin primes; sequence gives values of p+2 such that (q_k)^2 > q_{k-i}*q_{k+i} for all 1 <= i <= k-1.at n=19A021007
- n-th prime p(k) such that p(k) + p(k+9) = p(k+3) + p(k+6).at n=22A022893