15247
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 15520
- Proper Divisor Sum (Aliquot Sum)
- 273
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 14976
- Möbius Function
- 1
- Radical
- 15247
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- 71
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
- Restricted partitions.at n=21A049285
- a(n) = a(n-1) * a(n-1) - B * a(n-1) + B, a(0) = 1 + B for B = 7.at n=3A067686
- a(n) = n^4 + 5*n^2 + 1.at n=11A082113
- a(n) = floor(11^n/9^n).at n=48A094997
- Numbers k such that tau(k) = tau(k+1) mod 691, where tau is Ramanujan's tau function A000594.at n=24A121733
- a(n) = 14*n^2 + 1.at n=32A158482
- Totally multiplicative sequence with a(p) = a(p-1) + 7 for prime p.at n=42A166704
- Expansion of x*(1 -15*x +99*x^2 -373*x^3 +879*x^4 -1338*x^5 +1311*x^6 -804*x^7 +289*x^8 -44*x^9) / [(1-3*x+x^2) *(1-2*x)^6 *(1-x)^2].at n=8A211387
- Values of n such that L(20) and N(20) are both prime, where L(k) = (n^2+n+1)*2^(2*k) + (2*n+1)*2^k + 1, N(k) = (n^2+n+1)*2^k + n.at n=36A227523
- Number of maximal triangle-free labeled graphs on n vertices.at n=7A280020
- Numbers k such that (13*10^k + 401)/9 is prime.at n=18A289811
- Solution of the complementary equation a(n) = a(n-1) + a(n-2) + b(n) + 2*n, where a(0) = 1, a(1) = 2, b(0) = 3, b(1) = 4, b(2) = 5, and (a(n)) and (b(n)) are increasing complementary sequences.at n=15A294170
- a(n) = prime(n) * prime(2n).at n=21A319613
- Starting at n, a(n) is the number of times we move from a positive spot to a spot we have already visited according to the following rules. On the k-th step (k=1,2,3,...) move a distance of k in the direction of zero. If the number landed on has been landed on before, move a distance of k away.at n=63A324684
- Nonprime Heinz numbers of multiples of triangular partitions, or of finite arithmetic progressions with offset 0.at n=30A325407
- Products of exactly two distinct primes in A090252, in order of appearance.at n=48A354160
- Products of exactly two distinct odd primes in A090252, in order of appearance.at n=46A354162
- Integers k for which A000594(k)^2 > 4 k^11, where A000594 is Ramanujan's tau function.at n=36A364087
- G.f. A(x) satisfies A(x) = 1 / ((1 + x) * (1 - x * A(x^4))).at n=54A367694
- After the initial 1, numbers k such that A347381 obtains its minimum value at k, of all the divisors d of k larger than one, where A347381 is the distance from n to the nearest common ancestor of n and sigma(n) in the Doudna-tree (A005940).at n=20A374218