8642
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
- 5
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 13500
- Proper Divisor Sum (Aliquot Sum)
- 4858
- 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
- 4144
- Möbius Function
- -1
- Radical
- 8642
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 3
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
- 171
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- yes
- Odd
- no
Appears in sequences
- a(0) = 1, a(n) = 15*n^2 + 2 for n>0.at n=24A010005
- Pisot sequences E(5,7), P(5,7).at n=20A020711
- Pisot sequences E(7,10), P(7,10).at n=19A020721
- n written in fractional base 10/8.at n=32A024663
- Concatenate first n even numbers in reverse order.at n=3A038396
- Number of partitions satisfying cn(2,5) + cn(3,5) < cn(1,5) + cn(4,5).at n=34A039893
- Base-8 palindromes that start with 2.at n=25A043022
- Numbers of the form (10*a + b)^2 + (10*b + a)^2 with a and b less than 10, in numerical order.at n=37A061191
- Smallest multiple of n with property that digits are even and each digit is two less (mod 10) than the previous digit, if such a multiple exists; otherwise -1.at n=29A062885
- t(n^2) is a square and sets a new record for such squares, where t(n) = (sigma(n)-n)*omega(n); or t(n)= A001065(n)*A001221(n).at n=8A063777
- Total number of odd parts in all partitions of n.at n=23A066897
- Floor[ concatenation of n+4, n+3, n+2, n+1 and n divided by 5].at n=0A075006
- a(n) = A076803(n)/n.at n=4A077691
- Number of partitions of n such that the set of odd parts has only one element.at n=47A090868
- Let b(0)=1/2, b(n) = b(n-1) + Prime[n]/2; a(n)=b(2*n).at n=42A112039
- Number of partitions of n in which each part, with the possible exception of the largest, occurs at least three times.at n=51A116932
- Numbers with even decimal digits in decreasing order.at n=29A119261
- Expansion of (eta(q^4) * eta(q^12) / (eta(q) * eta(q^3)))^2 in powers of q.at n=16A123647
- Integer part of Gauss's Arithmetic-Geometric Mean M(1,n^3).at n=40A127759
- a(n) = floor(sqrt(a(n-1)^2 + a(n-2)^2 + a(n-1)*a(n-2))), a(1)=1, a(2)=3.at n=23A128424