2657
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2658
- 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
- 2656
- Möbius Function
- -1
- Radical
- 2657
- 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
- 53
- 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
- 384
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Numbers k such that phi(2k-1) < phi(2k), where phi is Euler's totient function A000010.at n=41A001836
- Quartan primes: primes of the form x^4 + y^4, x > 0, y > 0.at n=9A002645
- Numbers that are the sum of 2 positive 4th powers.at n=24A003336
- Numbers that are the sum of at most 2 nonzero 4th powers.at n=32A004831
- Primes p such that 1 + product of primes up to p is prime.at n=9A005234
- Number of acyclic ketone and aldehyde stereo-isomers with n carbon atoms.at n=10A005957
- Primes p == 1 (mod 8), p = a^2 +64*b^2 such that y^2 = x^3 + p*x has rank 0.at n=8A007765
- If a, b in sequence, so is ab+7.at n=24A009312
- Primes p == 1 mod 8 such that 2 and -2 are both 4th powers (one implies other) mod p.at n=43A014754
- Numbers k such that the continued fraction for sqrt(k) has period 35.at n=5A020374
- Let q_k=p(p+2) be product of k-th pair of twin primes; sequence gives values of p such that (q_k)^2 > q_{k-i}q_{k+i} for all 1 <= i <= k-1.at n=24A021005
- Initial members of prime triples (p, p+2, p+6).at n=27A022004
- Coordination sequence T2 for Zeolite Code CGS.at n=38A027366
- Coordination sequence T4 for Zeolite Code CGS.at n=38A027368
- Primes of the form k^2 + k + 5.at n=18A027755
- a(n) = prime(9*n - 3).at n=42A031390
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 22 ones.at n=27A031790
- a(n) = prime(10*n - 6).at n=38A031914
- Upper prime of a difference of 10 between consecutive primes.at n=35A031929
- Primes of form x^2+38*y^2.at n=30A033226