2971
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2972
- 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
- 2970
- Möbius Function
- -1
- Radical
- 2971
- 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
- 48
- 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
- 429
- 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=14A000230
- Indices of prime Fibonacci numbers.at n=21A001605
- Smallest primitive factor of 2^(2n+1) + 1.at n=27A002185
- Primes of form k^2 + k + 1.at n=18A002383
- Centered triangular numbers: a(n) = 3*n*(n-1)/2 + 1.at n=44A005448
- Number of n-node animals on f.c.c. lattice (invert A007199).at n=5A006194
- 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=26A021007
- Primes that remain prime through 2 iterations of function f(x) = 6x + 1.at n=30A023256
- a(n) = least m such that if r and s in {1/2, 1/4, 1/6, ..., 1/2n} satisfy r < s, then r < k/m < (k+1)/m < s for some integer k.at n=29A024835
- Square of the lower triangular normalized partition matrix.at n=16A027516
- Second column of A027516.at n=4A027529
- Palindromic primes in base 16 (or hexadecimal), but written here in base 10.at n=31A029732
- Primes with property that when squared all even digits occur together and all odd digits occur together.at n=33A030480
- a(n) = prime(10*n - 1).at n=42A031376
- 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 53.at n=15A031551
- Lucky numbers with size of gaps equal to 10 (upper terms).at n=33A031893
- Primes of form x^2+95*y^2.at n=20A033206
- Prime closest to e^n.at n=8A037028
- Largest prime < e^n.at n=7A040016
- a(n)=(s(n)+5)/9, where s(n)=n-th base 9 palindrome that starts with 4.at n=26A043075