15858
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 27
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 34398
- Proper Divisor Sum (Aliquot Sum)
- 18540
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5280
- Möbius Function
- 0
- Radical
- 5286
- Omega Function (Ω)
- 4
- 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
- 146
- 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
- Let (u1,u2) be successive untouchable numbers such that phi(u1) = phi(u2); sequence gives values of u2.at n=33A048190
- Least k such that (k*M(n))^2+k*M(n)-1 is the first of a pair of twin primes, where M(n) = Mersenne primes.at n=11A109342
- Least number k such that (k*M(n))^2 + k*M(n) - 1 and (k*M(n))^2 + k*M(n) + 1 are twin primes where M(n) is the n-th Mersenne prime.at n=11A121371
- a(n) = 49*n^2 - n.at n=17A157923
- a(n) = 196*n^2 - 2*n.at n=8A158224
- a(n) = 324*n^2 - 18.at n=6A158589
- Number of binary strings of length n with no substrings equal to 0001 or 1100.at n=17A164400
- a(n) is the smallest positive integer such that a(n)*n is an anagram of a(n)*8.at n=26A175697
- Numbers k such that phi(k-6) = phi(k) = phi(k+6).at n=22A217006
- Triangle read by rows: coefficients of the polynomials A_{1,7}(n,k).at n=18A245170
- Solution of the complementary equation a(n) = a(n-1) + a(n-2) + b(n) + 1, where a(0) = 1, a(1) = 3, b(0) = 2, b(1) = 4, b(2) = 5, and (a(n)) and (b(n)) are increasing complementary sequences.at n=16A295953
- Number of compositions of n with strictly increasing run-lengths.at n=44A333192
- Ordered lone-child-avoiding trees where vertices have decreasing subtree sizes.at n=18A346787