1581
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 2304
- Proper Divisor Sum (Aliquot Sum)
- 723
- 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
- 960
- Möbius Function
- -1
- Radical
- 1581
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 78
- Smith Number
- yes
- 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
- Expansion of 1/((1-x)^2*(1-x^2)*(1-x^3)).at n=35A000601
- Apply partial sum operator twice to Fibonacci numbers.at n=13A001924
- Divisors of 2^40 - 1.at n=38A003546
- Coordination sequence T1 for Zeolite Code AFT.at n=30A008026
- Coordination sequence T3 for Zeolite Code NON.at n=24A008214
- a(n) = floor(n*(n - 1)*(n - 2)/32).at n=38A011914
- Partial sums of A003136.at n=35A014146
- Expansion of 1/(1-x^4-x^5-x^6-x^7-x^8-x^9-x^10-x^11-x^12-x^13-x^14).at n=29A017836
- Powers of fifth root of 17 rounded down.at n=13A018162
- Fermat pseudoprimes to base 4.at n=13A020136
- Pseudoprimes to base 16.at n=18A020144
- Pseudoprimes to base 35.at n=10A020163
- Pseudoprimes to base 47.at n=23A020175
- Pseudoprimes to base 64.at n=51A020192
- Pseudoprimes to base 89.at n=28A020217
- a(n) = n*(11*n - 1)/2.at n=17A022268
- a(n) is the position of square of n-th prime among the powers of primes (A000961).at n=29A024624
- Positions of squares among the powers of primes (A000961).at n=40A024626
- Position of n^2 + 5 in A000408.at n=43A024801
- Position of n^3 + 9 in A024975.at n=23A024979