9639
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 27
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 20
- Divisor Sum
- 17424
- Proper Divisor Sum (Aliquot Sum)
- 7785
- 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
- 5184
- Möbius Function
- 0
- Radical
- 357
- Omega Function (Ω)
- 6
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 135
- Smith Number
- yes
- 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
- no
- Odd
- yes
Appears in sequences
- Geometric mean of phi(n) and sigma(n) is an integer, n odd.at n=23A015705
- Numbers k such that k^4 can be written as a sum of four positive 4th powers with no common factor.at n=33A039664
- Odd numbers divisible by exactly 6 primes (counted with multiplicity).at n=30A046319
- a(n)=a(n-1)+a(m), where m=2n-2-2^(p+1) and 2^p<n-1<=2^(p+1), for n >= 4.at n=29A050067
- Number of primitive (period n) step cyclic shifted sequence structures using exactly three different symbols.at n=13A056445
- Numbers k such that k | 11^k + 10^k + 9^k + 8^k + 7^k + 6^k + 5^k + 4^k + 3^k.at n=33A057286
- Number of simple, connected, unit-distance graphs on n points realizable in the plane with straight edges all of the same length; lines are permitted to cross.at n=8A059103
- Least m such that n = m mod tau(m) if such m exists, otherwise 0.at n=18A066708
- Numbers k such that phi(k) and sigma(k) are both perfect squares.at n=11A067781
- Numbers k such that k = (sum of distinct prime factors of k)*(product of distinct prime factors of k).at n=39A068999
- Smallest odd number k such that p(2m)-2p(m)=k has exactly n solutions (where p(m) = m-th prime).at n=11A069890
- Numbers k such that the sum of the digits of k equals the sum of the prime divisors of k.at n=39A070275
- Smallest multiple of n^2 beginning and ending in n, or 0 if no such multiple exists.at n=8A078211
- Iccanobirt numbers (6 of 15): a(n) = R(a(n-1)) + R(a(n-2)) + a(n-3), where R is the digit reversal function A004086.at n=14A102116
- Negative of column k=3 sequence of array A103728.at n=10A103730
- n^2 * (n^3 + 2n^2 + 7n - 2) / 8.at n=9A106845
- a(n) = (10^k - n)(10^k + n), where k is the number of digits in n.at n=18A110397
- Smallest term in the Hofstadter sequence A005243 having exactly n representations as sum of consecutive earlier terms.at n=12A118166
- Positive numbers of the form -x^4+6x^2 y^2-y^4 (where x,y are integers).at n=36A135790
- a(n) = Fibonacci(n)*A109041(n) for n>=1, with a(0)=1, where A109041 lists the coefficients in eta(q)^9/eta(q^3)^3.at n=8A205973