1657
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
- 1658
- 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
- 1656
- Möbius Function
- -1
- Radical
- 1657
- 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
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 260
- 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).at n=21A001837
- Numbers k such that 25*4^k + 1 is prime.at n=21A002263
- Cuban primes: primes which are the difference of two consecutive cubes.at n=11A002407
- Hex (or centered hexagonal) numbers: 3*n*(n+1)+1 (crystal ball sequence for hexagonal lattice).at n=23A003215
- Smallest number that requires n iterations of the unitary totient function (A047994) to reach 1.at n=15A003271
- Numbers that are the sum of 12 positive 6th powers.at n=28A003368
- Shifts one place left under 4th-order binomial transform.at n=5A004213
- Class 4+ primes (for definition see A005105).at n=28A005108
- Class 4- primes (for definition see A005109).at n=41A005112
- Primes p such that 2p-1 is also prime.at n=47A005382
- Primes p such that (p+1)/2 is prime.at n=30A005383
- x^3 + n*y^3 = 1 is solvable.at n=36A005988
- Odd numbers not of form p + 2^k (de Polignac numbers).at n=34A006285
- Where the prime race among 5k+1, ..., 5k+4 changes leader.at n=14A007353
- Number of strict 3rd-order maximal independent sets in cycle graph.at n=34A007392
- Primes of form n^2 + n + 17.at n=31A007635
- Coordination sequence T1 for Zeolite Code AWW.at n=29A008045
- Expansion of tan(tan(x))/cosh(x) (odd powers only).at n=3A009702
- 4th differences of Bell numbers.at n=4A011967
- Apply (1+Shift)^3 to Bell numbers.at n=7A011970