1608
domain: N
Properties
Digital Properties
- Digit Count
- 4
- 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
- 4080
- Proper Divisor Sum (Aliquot Sum)
- 2472
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 528
- Möbius Function
- 0
- Radical
- 402
- Omega Function (Ω)
- 5
- 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
- 21
- 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
- Numbers k such that phi(k) = phi(k+2).at n=31A001494
- Number of equivalence classes of binary sequences of primitive period n.at n=18A002730
- Number of Hamiltonian paths in W_4 X P_n.at n=2A003766
- Coordination sequence T1 for Zeolite Code PHI.at n=29A008227
- Coordination sequence T2 for Zeolite Code WEI.at n=28A009918
- a(n) = floor(binomial(n,8)/8).at n=16A011854
- Average of twin prime pairs.at n=50A014574
- Seidel's triangle, read by rows.at n=32A014781
- Fibonacci sequence beginning 2, 28.at n=10A022376
- a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2) and t is A000201 (lower Wythoff sequence).at n=21A023866
- a(n) = [ C(2n,n)/n ].at n=7A024498
- a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n+1-k), where k = [ (n+1)/2 ], s = (F(2), F(3), ...).at n=11A024591
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (natural numbers), t = A000201 (lower Wythoff sequence).at n=20A024863
- a(n) = Sum_{k=1..n} k*floor(n/k); also Sum_{k=1..n} sigma(k) where sigma(n) = sum of divisors of n (A000203).at n=43A024916
- a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n-k+1), where k = [ n/2 ], s = (F(2), F(3), F(4), ...).at n=10A025105
- Index of 7^n within the sequence of the numbers of the form 4^i*7^j.at n=47A025722
- a(n) = T(n,n), T given by A026552. Also a(n) is the number of integer strings s(0),...,s(n) counted by T, such that s(n)=0.at n=10A026553
- a(n) = self-convolution of row n of array T given by A026519.at n=5A027262
- Self-convolution of row n of array T given by A026552.at n=5A027272
- Least term in period of continued fraction for sqrt(n) is 10.at n=7A031434