2557
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
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2558
- 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
- 2556
- Möbius Function
- -1
- Radical
- 2557
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 133
- 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
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 375
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Numbers k such that (1,k) is "good".at n=35A000696
- Primes p of the form 3k+1 such that sum_{x=1..p} cos(2*Pi*x^3/p) < -sqrt(p).at n=35A000923
- Numbers k such that phi(2k+1) < phi(2k).at n=33A001837
- Primes p such that (p+1)/2 is prime.at n=39A005383
- Primes of the form m^2 + 3m + 9, where m can be positive or negative.at n=19A005471
- Number of partitions of an n-set into boxes of size >2.at n=10A006505
- Number of non-Hamiltonian polyhedra with n faces.at n=11A007032
- Coordination sequence T1 for Zeolite Code MER.at n=37A008160
- Coordination sequence T1 for Zeolite Code MFI.at n=32A008161
- Coordination sequence T6 for Zeolite Code PAU.at n=37A008224
- Coordination sequence T1 for Zeolite Code -CHI.at n=32A009846
- Coordination sequence T4 for Zeolite Code CGF.at n=35A019454
- Primes whose digits are primes; primes having only {2, 3, 5, 7} as digits.at n=28A019546
- Numbers k such that the continued fraction for sqrt(k) has period 23.at n=7A020362
- n-th prime p(k) such that p(k) + p(k+9) = p(k+3) + p(k+6).at n=30A022893
- Primes that remain prime through 2 iterations of the function f(x) = 2x + 5.at n=36A023243
- Primes that remain prime through 2 iterations of the function f(x) = 3*x + 2.at n=28A023246
- Primes that remain prime through 2 iterations of function f(x) = 9x + 8.at n=36A023267
- a(n) is the position of square of n-th prime among the powers of primes (A000961).at n=34A024624
- Positions of squares among the powers of primes (A000961).at n=48A024626