9100
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 10
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 36
- Divisor Sum
- 24304
- Proper Divisor Sum (Aliquot Sum)
- 15204
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 2880
- Möbius Function
- 0
- Radical
- 910
- Omega Function (Ω)
- 6
- Little Omega Function (ω)
- 4
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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 21
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- yes
- Odd
- no
Appears in sequences
- Numbers k such that 17*2^k - 1 is prime.at n=26A001774
- Take solution to Pellian equation x^2 - n*y^2 = 1 with smallest positive y and x >= 0; sequence gives a(n) = y, or 0 if n is a square. A002350 gives values of x.at n=52A002349
- a(n) = n*(n+4)*(n+5)/6.at n=35A005586
- Unitary harmonic numbers (those for which the unitary harmonic mean is an integer).at n=12A006086
- [ exp(13/22)*n! ].at n=6A030833
- Every run of digits of n in base 6 has length 2.at n=33A033004
- Smallest positive integer y satisfying the Pell equation x^2 - D*y^2 = 1 for nonsquare D.at n=45A033317
- Incrementally largest values of minimal y satisfying Pell equation x^2-Dy^2=1.at n=7A033319
- Denominators of continued fraction convergents to sqrt(53).at n=9A041091
- Denominators of continued fraction convergents to sqrt(477).at n=9A041911
- Numbers k such that 265*2^k + 1 is prime.at n=18A053349
- Exponential transform of Stirling1 triangle A008275.at n=25A055924
- a(n) = Product_{k|n} (n+1-k).at n=25A056819
- Number of permutations in the symmetric group S_n whose order is 1 or prime.at n=7A060181
- Infinitary harmonic numbers: harmonic mean of infinitary divisors is an integer.at n=11A063947
- Let u be any string of n digits from {0,1,2}; let f(u) = number of distinct primes, not beginning with 0, formed by permuting the digits of u to a base-3 number; then a(n) = max_u f(u).at n=12A065844
- Integers which have at least two different factorizations into coprime parts whose sum are equal.at n=37A069064
- Numbers n such that sopf(sigma(n)) = sigma(sopf(n)), where sopf(x) = sum of the distinct prime factors of x.at n=22A076532
- a(n) = n*(n - 1)*(n + 2)/2.at n=25A077414
- Let p = n-th prime, take smallest solution (x,y) to the Pellian equation x^2 - p*y^2 = 1 with x and y >= 1; sequence gives value of y.at n=15A081234