15581
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 15582
- Proper Divisor Sum (Aliquot Sum)
- 1
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 15580
- Möbius Function
- -1
- Radical
- 15581
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- 84
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 1817
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Number of n-bead bracelets (turnover necklaces) with 8 red beads and n-8 black beads.at n=16A005514
- a(n) is the sum over all floor(k^3/n), k=0 to n inclusive.at n=38A014818
- Primes that remain prime through 3 iterations of function f(x) = 4x + 3.at n=39A023281
- Primes that remain prime through 4 iterations of function f(x) = 4x + 3.at n=10A023311
- Primes that are palindromic in base 9.at n=32A029977
- Centered 19-gonal numbers.at n=40A069132
- Number of subsets of {1, ..., n} that are double-free but not sum-free.at n=17A088810
- Smaller pair of the primes described in A116074.at n=1A116075
- Lesser of twin primes isolated from neighboring primes by +- 10 (or more).at n=28A138063
- Primes of the form 210k + 41.at n=38A140848
- Primes congruent to 15 mod 43.at n=38A142264
- Primes congruent to 24 mod 47.at n=39A142375
- Primes congruent to 52 mod 53.at n=34A142582
- Primes congruent to 5 mod 59.at n=34A142732
- Primes congruent to 26 mod 61.at n=27A142824
- a(n) = (n^3 + 18*n^2 + 17*n + 6)/6.at n=40A143058
- Prime numbers p such that p - 1 is the fourth a-figurate number and nineteenth b-figurate number for some a and b.at n=14A144327
- Primes of the form (5+ a triangular number A000217).at n=23A159049
- Number of binary strings of length n with no substrings equal to 0000 or 0101.at n=16A164389
- Primes of the form 43*n^2 + 3*n + 1.at n=32A185658