15045
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 25920
- Proper Divisor Sum (Aliquot Sum)
- 10875
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7424
- Möbius Function
- 1
- Radical
- 15045
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 4
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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 40
- 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
- Convolution of A001950 with itself.at n=22A023667
- Terms of A050530 with four prime divisors.at n=5A053340
- a(n) = n + max{ a(i)*a(n-i) ; 1 <= i <= n-1 }, a(n) = n for n <= 2.at n=16A054253
- a(n) = A077702(n+1)/A077702(n).at n=13A077703
- Odd composite numbers k such that cototient(k) - phi(k) = k - 2*phi(k) is an odd prime.at n=6A083255
- a(n) = A088418(n+1)/A088418(n).at n=13A088419
- a(n) = K_3(n) = Sum_{k>=0} A090285(3,k)*2^k*binomial(n,k). a(n) = (4*n^3+30*n^2+56*n+15)/3.at n=20A090294
- Primitive elements of A119432.at n=32A119433
- Triangle of coefficients of p(x,n) = (1/3)*(1-x)^(n+1)*Sum_{m >= 0} ((5*m+4)^n - (5*m+1)^n)*x^m, read by rows.at n=16A154855
- Partial sums of A079062.at n=33A177455
- Riordan array (1, x*(1-x)/(1-3*x+x^2)).at n=47A188137
- Number of ways to place 4 nonattacking semi-queens on an n X n board.at n=6A202655
- Number of n X 2 0,1 arrays indicating 2 X 2 subblocks of some larger (n+1) X 3 binary array having a sum of three or less, with rows and columns of the latter in lexicographically nondecreasing order.at n=23A227265
- Products p*q*r*s of distinct primes for which (p*q*r*s + 1)/2 is prime.at n=31A234501
- Number of (5+1) X (n+1) 0..1 arrays with every 2 X 2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically.at n=9A258558
- Number of (3+1) X (n+1) arrays of permutations of 0..n*4+3 with each element having directed index change -2,-2 -1,0 0,1 or 1,0.at n=9A264536
- Odd numbers that are not of the form p + 2^a + 2^b with b > a > 0, and p prime.at n=5A268693
- Numbers n such that cototient(n) does not divide phi(n!).at n=2A291597
- Number of compositions of n where the difference between largest and smallest parts equals seven.at n=13A323124
- Terms of A051488 that do not belong to A083207.at n=3A333232