1565
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 1884
- Proper Divisor Sum (Aliquot Sum)
- 319
- 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
- 1248
- Möbius Function
- 1
- Radical
- 1565
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 122
- 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
- Coefficients in expansion of permanent of infinite tridiagonal matrix shown below.at n=49A003113
- Let y=f(x) satisfy F(x,y)=0. a(n) is the number of terms in the expansion of (d/dx)^n y in terms of the partial derivatives of F.at n=8A003262
- Number of protruded partitions of n with largest part at most 4.at n=11A005405
- Spiral sieve using Fibonacci numbers.at n=15A005623
- Number of unsensed 2-connected planar maps with n edges.at n=9A006403
- Coordination sequence T4 for Zeolite Code NON.at n=24A008215
- Numbers k such that k | 5^k + 5.at n=7A015891
- Smallest odd k>n such that k | n^k + n, or 0 if n=2^m.at n=5A015908
- Positive integers n such that 2^n == 2^5 (mod n).at n=50A015925
- Sum of gcd(x, y) for 1 <= x, y <= n.at n=25A018806
- Numbers k such that the continued fraction for sqrt(k) has period 17.at n=12A020356
- a(n) = (n/2)*(n^4 + 1).at n=5A021003
- Index of 5^n within sequence of numbers of form 2^i * 5^j.at n=36A022334
- Numbers k such that Fibonacci(k) == -5 (mod k).at n=44A023165
- Least m such that if r and s in {1/2, 1/5, 1/8,..., 1/(3n-1)}, satisfy r < s, then r < k/m < s for some integer k.at n=26A024823
- a(1) = 3; a(n+1) = a(n)-th nonprime, where nonprimes begin at 0.at n=23A025000
- Index of 6^n within the sequence of the numbers of the form 3^i*6^j.at n=43A025713
- Index of 9^n within the sequence of the numbers of the form 5^i*9^j.at n=47A025735
- a(n) = A026568(n,n-1), also a(n) = number of integer strings s(0),...,s(n) counted by A026568 such that s(n)=1.at n=9A026570
- a(n) = (1/2)*(n-th largest even number in array T given by A027170).at n=44A027184