15120
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 9
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 80
- Divisor Sum
- 59520
- Proper Divisor Sum (Aliquot Sum)
- 44400
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 3456
- Möbius Function
- 0
- Radical
- 210
- Omega Function (Ω)
- 9
- 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
- yes
- 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
- 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 A(n) = #{(i,j): i^2 + j^2 <= n}, V(n) = Pi*n, P(n) = A(n) - V(n); sequence gives values of n where |P(n)| sets a new record.at n=38A000099
- a(n) = (2*n+1)! / n!.at n=4A000407
- Differences of 0: 6!*Stirling2(n,6).at n=6A000920
- Lah numbers: a(n) = (n-1)*n!/2.at n=5A001286
- a(n) = n!/24.at n=5A001720
- Highly composite numbers: numbers n where d(n), the number of divisors of n (A000005), increases to a record.at n=21A002182
- Denominator of Sum_{i+j+k=n; i,j,k > 0} 1/(i*j*k).at n=6A002546
- Largest number in n-th row of triangle of Lah numbers (A008297 and A271703).at n=7A002868
- Smallest number with 2n divisors.at n=39A003680
- Superabundant [or super-abundant] numbers: n such that sigma(n)/n > sigma(m)/m for all m < n, sigma(n) being A000203(n), the sum of the divisors of n.at n=20A004394
- Where records occur in A038548.at n=18A004778
- Theta series of {E_6}* lattice.at n=29A005129
- a(1)=1; a(n) = n!*Fibonacci(n+2), n > 1.at n=5A005922
- The minimal numbers: sequence A005179 arranged in increasing order.at n=41A007416
- a(n) = f(a(n-1)), with f(m) = Sum i*b(i)*2^(i-1), m = Sum b(i)*2^i, and starting value 16.at n=6A007824
- Triangle T(n,k) = n!/(n-k)! (0 <= k <= n) read by rows, giving number of permutations of n things k at a time.at n=50A008279
- a(n) is the concatenation of n and 8n.at n=14A009470
- E.g.f. sin(x^2)/2, coefficients of x^(4*n + 2).at n=2A009564
- a(n) = (n+1)*(2*n+1)*(3*n+1).at n=13A011199
- sec(sinh(x)*arcsin(x))=1+12/4!*x^4+240/6!*x^6+15120/8!*x^8...at n=4A012543