2585
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
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 3456
- Proper Divisor Sum (Aliquot Sum)
- 871
- 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
- 1840
- Möbius Function
- -1
- Radical
- 2585
- 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
- 53
- 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
- no
- Odd
- yes
Appears in sequences
- Essentially the same as A001611.at n=16A000381
- a(n) = Fibonacci(n) + 1.at n=18A001611
- Numbers of the form (p^2 - 49)/120 where p is prime.at n=50A002382
- Number of trees in an n-node wheel.at n=17A002985
- Inverse Möbius transform of A003965.at n=52A003981
- a(n) = round(1000*log_2(n)).at n=5A004266
- a(n) = ceiling(1000*log_2(n)).at n=5A004267
- a(n) = ceiling(n*phi^9), where phi is the golden ratio, A001622.at n=34A004964
- Coordination sequence T1 for Zeolite Code MTW.at n=33A008196
- a(n) = Fibonacci(n) + (-1)^n.at n=18A008346
- Partial sums of primes, if 1 is regarded as a prime (as it was until quite recently, see A008578).at n=37A014284
- Numbers k such that sigma(k) = sigma(k+4).at n=6A015863
- Pisot sequences L(4,6), E(4,6).at n=14A020706
- Pisot sequences L(6,9), E(6,9).at n=13A020717
- a(n) = [ a(n-1)/a(1) ] + [ a(n-2)/a(2) ] + ... + [ a(1)/a(n-1) ], for n >= 3.at n=20A022876
- a(n) = position of n^2 + (n+1)^2 + (n+2)^2 in A004432.at n=31A024809
- Quasi-Carmichael numbers to base -7: squarefree composites n such that prime p|n ==> p+7|n+7.at n=3A029567
- Numbers with exactly five distinct base-7 digits.at n=18A031984
- Numbers in which all pairs of consecutive base-10 digits differ by 3.at n=45A033081
- a(n+1) = a(n) + sum of squares of digits of a(n).at n=38A033936