6990
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 24
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 16848
- Proper Divisor Sum (Aliquot Sum)
- 9858
- 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
- 1856
- Möbius Function
- 1
- Radical
- 6990
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 57
- 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
- yes
- Odd
- no
Appears in sequences
- a(n) = 10000*log_10(n) rounded to the nearest integer.at n=4A004229
- a(n) = 10000*log_10(n) rounded up.at n=4A004230
- Eight iterations of Reverse and Add are needed to reach a palindrome.at n=19A015988
- Fibonacci sequence beginning 0, 30.at n=13A022364
- 18-gonal (or octadecagonal) numbers: a(n) = n*(8*n-7).at n=30A051870
- Numbers which need eight 'Reverse and Add' steps to reach a palindrome.at n=14A065213
- a(n) = (1/24)*(sigma_3(2*n-1) - sigma_1(2*n-1)).at n=27A081861
- Numbers k such that 2*10^k + 7*R_k - 6 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=8A098960
- Indices of primes in sequence defined by A(0) = 89, A(n) = 10*A(n-1) - 31 for n > 0.at n=17A101073
- Write the natural numbers as an infinite sequence of digits, starting at the left; a(n) is the subset (i.e., the position in this sequence of the "counting digits") of the first digit of the n-th square.at n=44A105314
- Least positive k such that k * [RSA-200]^n - 1 is prime, where RSA-200 is the 200 decimal digit RSA challenge number A391940(15).at n=24A108375
- Numbers k such that the sum of the first k primes is prime and the sum of the squares of the first k primes is also prime.at n=32A124225
- a(n) = 8*n^4+44*n^3+106*n^2+100*n+30.at n=5A129029
- Number of distinct Markov type classes of order 4 possible in binary strings of length n.at n=10A132299
- Aliquot sequence starting at 3630.at n=3A143930
- a(n) = 250*n - 10.at n=27A154378
- Integer part of the volume of a regular tetrahedron with edge length n.at n=38A171973
- Coefficients of the sum 1+ x/(1-x) + x^2/(1-x^2) + x^3/ ( (1-x)(1-x^2)) + x^4/ ( (1-x)(1-x^3) ) + x^5/ ( (1-x)(1-x^4) ) + x^5 /((1-x^2)(1-x^3)) + x^6/ ( (1-x)(1-x^2)(1-x^3)) + ...at n=39A178702
- Where zeros occur in the 1-0 race in the binary expansion of Pi-3; that is, n such that A174832(n) = 0.at n=37A178980
- Triangle, read by rows, where T(n,k) equals the sum of (n-k) terms in row n of triangle A131338 starting at position nk - k(k-1)/2, with the main diagonal formed from the row sums.at n=60A183202