8157
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 10880
- Proper Divisor Sum (Aliquot Sum)
- 2723
- 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
- 5436
- Möbius Function
- 1
- Radical
- 8157
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- 65
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- Squarefree Number
- yes
- 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
- no
- Odd
- yes
Appears in sequences
- a(n) = [ a(n-1)/a(1) ] + [ a(n-3)/a(3) ] + [ a(n-5)/a(5) ] + ..., for n >= 3.at n=37A022872
- 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 60.at n=25A031558
- StirlingS2[ n,m ] triangle summed down the columns.at n=40A036560
- Numbers whose base-4 representation contains exactly three 1's and four 3's.at n=13A045128
- Discriminants of real quadratic fields with class number 1 and related continued fraction period length of 18.at n=41A050967
- Rounded base-3 logarithm of A082126(n).at n=24A082127
- Number of digits in A110782(n).at n=14A110783
- Numbers whose square is the concatenation of two numbers k and k-4.at n=1A115443
- Row sums of triangle A132729.at n=12A132730
- Triangle read by rows: T(n, k) = Sum_{i=0..n} Stirling2(i, k).at n=50A137596
- Triangle read by rows, A000012 * A008277.at n=40A137649
- Partial sums of A000141.at n=11A175361
- Numbers k such that there are 2 primes between 100*k and 100*k + 99.at n=22A186394
- Where the difference A055938(n) - A005187(n) obtains record values; positions of records in A257126.at n=17A257130
- Decimal representation of the diagonal from the corner to the origin of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 525", based on the 5-celled von Neumann neighborhood.at n=12A288901
- G.f.: exp( Sum_{n>=1} A322205(n)*x^n/n ), where A322205(n) is the coefficient of x^(2*n)*y^n/n in Sum_{n>=1} -log(1 - (x^n + y^n)).at n=7A322206
- Number of integer partitions y of n such that Product_{i in y} prime(i)/i is an integer.at n=53A324925