1669
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 1670
- 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
- 1668
- Möbius Function
- -1
- Radical
- 1669
- 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
- 135
- 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
- 263
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- a(0)=2; for n>=1, a(n) = smallest prime p such that there is a gap of exactly 2n between p and next prime, or -1 if no such prime exists.at n=12A000230
- Primes p of the form 3k+1 such that -sqrt(p) < sum_{x=1..p} cos(2*Pi*x^3/p) < sqrt(p).at n=37A000922
- From a Goldbach conjecture: records in A185091.at n=23A002092
- Let i, i+d, i+2d, ..., i+(n-1)d be an n-term arithmetic progression of primes; choose the one which minimizes the last term; then a(n) = last term i+(n-1)d.at n=7A005115
- Coordination sequence T2 for Zeolite Code AFR.at n=31A008020
- Coordination sequence T2 for Zeolite Code DAC.at n=26A008068
- Coordination sequence T3 for Zeolite Code MFI.at n=26A008166
- Coordination sequence T1 for Zeolite Code -PAR.at n=29A009855
- Least m such that the continued fraction for sqrt(m) has period n.at n=53A013646
- 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=17A014424
- Primes p==1 (mod 6) such that 3 and -3 are both cubes (one implies other) modulo p.at n=40A014753
- Expansion of x/(1 - 5*x - 12*x^2).at n=5A015548
- Numbers k such that the continued fraction for sqrt(k) has period 53.at n=0A020392
- Smallest nonempty set S containing prime divisors of 6k+7 for each k in S.at n=43A020604
- 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=20A021007
- Primes that remain prime through 2 iterations of the function f(x) = 2x + 5.at n=25A023243
- Primes that remain prime through 2 iterations of the function f(x) = 2x + 9.at n=36A023245
- Convolution of A000201 and A014306.at n=48A023666
- Sum{T(n-k,k)}, 0<=k<=[ n/2 ], where T is the array in A026374.at n=14A026385
- Prime p concatenated with next prime is also prime.at n=38A030459