1520
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 8
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 20
- Divisor Sum
- 3720
- Proper Divisor Sum (Aliquot Sum)
- 2200
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 576
- Möbius Function
- 0
- Radical
- 190
- 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
- yes
- 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
- 109
- Smith Number
- no
- 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
- yes
- Odd
- no
Appears in sequences
- Number of ways of writing n as a sum of 5 squares.at n=19A000132
- Pentagonal numbers: a(n) = n*(3*n-1)/2.at n=32A000326
- Number of ways of writing 0 as Sum_{k=-n..n} e(k)*k, where e(k) is 0 or 1.at n=7A000980
- Numbers that are the sum of 3 nonnegative cubes in more than 1 way.at n=10A001239
- Take solution to Pellian equation x^2 - n*y^2 = 1 with smallest positive y and x >= 0; sequence gives a(n) = x, or 1 if n is a square. A002349 gives values of y.at n=30A002350
- Low temperature series for spin-1/2 Ising magnetic susceptibility on 3-dimensional simple cubic lattice.at n=8A002926
- a(n) = floor(n*phi^9), where phi is the golden ratio, A001622.at n=20A004924
- a(n) = round(n*phi^9), where phi is the golden ratio, A001622.at n=20A004944
- a(n) = n*(n+2) = (n+1)^2 - 1.at n=38A005563
- a(n) = (n-1)*n*(n+4)/6.at n=20A005581
- Coefficients of modular function G_4(tau).at n=22A005762
- Numbers n such that 2^(2n+1) - 2^(n+1) + 1 is a prime.at n=14A006598
- Solution to a Pellian equation: least x such that x^2 - n*y^2 = +- 1.at n=30A006702
- Solution to Pellian: x such that x^2 - n y^2 = +- 1, +- 4.at n=30A006704
- Series for second parallel moment of square lattice (eventually changes sign).at n=6A006733
- Coordination sequence occurring in Zeolite Codes AFG, CAN, LIO, LOS.at n=27A008013
- Coordination sequence T1 for Zeolite Code APC.at n=27A008032
- Coordination sequence T4 for Zeolite Code EMT.at n=32A008089
- Coordination sequence T4 for Zeolite Code FER.at n=24A008109
- Theta series of D*_5 lattice.at n=76A008422