15457
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 17640
- Proper Divisor Sum (Aliquot Sum)
- 2183
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 13440
- Möbius Function
- -1
- Radical
- 15457
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 190
- Smith Number
- no
- 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
- Pseudoprimes to base 3.at n=28A005935
- Number of permutations that are 2 "block reversals" away from 12...n.at n=15A007972
- Pseudoprimes to base 14.at n=42A020142
- Pseudoprimes to base 42.at n=36A020170
- Pseudoprimes to base 55.at n=43A020183
- Strong pseudoprimes to base 32.at n=23A020258
- Strong pseudoprimes to base 50.at n=12A020276
- Strong pseudoprimes to base 73.at n=10A020299
- a(n) = (d(n)-r(n))/2, where d = A026063 and r is the periodic sequence with fundamental period (1,1,0,1).at n=46A026064
- Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 27.at n=2A031615
- a(n) = n*(2*n^2 - 3*n + 4)/3.at n=29A037235
- Base-3 Euler-Jacobi pseudoprimes.at n=11A048950
- a(n) = a(n-1) + a(n - 1 minus the number of terms of a(k) == (mod 4) so far).at n=33A060731
- a(n) = n^3 - 7*n + 7.at n=24A106734
- Nonprimes k such that 3^k == 3 (mod k).at n=36A122780
- a(n) = Sum_{k=0..n} k!*A124526(n+k,k) for n>=0.at n=6A124529
- a(n) = number of conjugacy classes in PSL_4(prime(n)).at n=10A124681
- Number of partitions of 2n-set in which number of blocks of size k is even (or zero) for every k.at n=5A130219
- a(n) = 7*n^2 + 14*n + 1.at n=46A131878
- Square table, read by antidiagonals, where row e.g.f.s, R(n,x), satisfy: d/dx log( R(n,x) ) = R(n+1,x)^(n+1) with R(n,0) = 1; that is, the logarithmic derivative of the e.g.f. of row n equals the e.g.f. of row n+1 to the n+1 power, for n>=0.at n=41A145085