12540
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 48
- Divisor Sum
- 40320
- Proper Divisor Sum (Aliquot Sum)
- 27780
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 2880
- Möbius Function
- 0
- Radical
- 6270
- Omega Function (Ω)
- 6
- Little Omega Function (ω)
- 5
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
- 63
- 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
- Number of planar partitions of n decreasing across rows.at n=21A003293
- a(n) = floor( n*(n-1)*(n-2)/19 ).at n=63A011901
- Floor[n(n-1)(n-2)(n-3)/14].at n=22A011924
- Expansion of e.g.f. sech(log(cos(x))) (even exponents only).at n=5A012009
- a(n) = n*(23*n + 1)/2.at n=33A022281
- Positive numbers k such that k and 2*k are anagrams in base 7 (written in base 7).at n=3A023068
- Positive numbers k such that k and 3*k are anagrams in base 7 (written in base 7).at n=16A023069
- Positive numbers k such that k and 4*k are anagrams in base 7 (written in base 7).at n=9A023070
- a(n) = (d(n)-r(n))/2, where d = A026046 and r is the periodic sequence with fundamental period (0,1,0,1).at n=38A026047
- "DHK[ 7 ]" (bracelet, identity, unlabeled, 7 parts) transform of 1,1,1,1,...at n=16A032248
- Numbers whose base-4 representation contains exactly three 0's and four 3's.at n=3A045080
- a(n) = a*b = x*y with (a-b) = (x+y) = A020882(n) (a>b, a>0, b>0, x>0, y>0), gcd(a, b) = gcd(x, y) = 1.at n=38A057229
- Sum of all parts of all partitions of n.at n=20A066186
- a(n)=phi(n^2+1)/n if (n^2+1) is composite and phi(n^2+1)==0 (mod n).at n=26A067926
- Numbers k such that the sign of core(k)-phi(k) is not equal to 2*mu(k)^2-1, where core(k) is the squarefree part of k.at n=18A070237
- Numbers k such that both k and 2*k are balanced numbers (A020492).at n=21A076375
- Numbers k such that (k-1, k+1) and (k/2-1, k/2+1) are both pairs of twin primes.at n=9A076504
- Numbers k such that binomial(prime(k), k) is divisible by k^2.at n=33A081384
- Triangle read by rows in which row n >= 1 gives coefficients in expansion of the polynomial Sum_{k=1..n} (1/n)*binomial(n,k)*binomial(n,k-1)*x^(2k)*(1+x)^(2n-2k) / x^2 in powers of x.at n=45A086873
- Sum of numbers under a triangle on a spiral staircase of width 10.at n=17A111080