7122
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 14256
- Proper Divisor Sum (Aliquot Sum)
- 7134
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- yes
Derived Values
- Euler's Totient
- 2372
- Möbius Function
- -1
- Radical
- 7122
- Omega Function (Ω)
- 3
- 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
- 49
- 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
- Sum of the products of the primes taken 2 at a time from the first n primes.at n=9A024447
- Number of 7's in all partitions of n.at n=36A024791
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 84.at n=6A031582
- Number of binary [ n,3 ] codes.at n=19A034357
- a(n)=(s(n)+3)/10, where s(n)=n-th base 10 palindrome that starts with 7.at n=34A043086
- a(n) = n^2 + (n + 1)^3 + (n + 2)^4.at n=7A061222
- a(n) = 5^n + 7^n + 8^n.at n=4A074574
- Multiples of 6 in which there is no common digit in successive terms.at n=23A083494
- Number of primes less than 10^n which do not contain the digit 0.at n=4A091634
- Slowest increasing sequence which self-describes its succession of odd and even digits.at n=38A105771
- Numbers k for which 14*k+1, 14*k+5, 14*k+11 and 14*k+13 are primes.at n=26A123987
- Sum of first n isolated (or single) primes A007510.at n=34A153478
- G.f. A(x) satisfies: 1-x = Sum_{n>=0} (-x)^n * A(x)^[n*phi], where phi = (sqrt(5)+1)/2.at n=8A199481
- a(n) = a(n-1) + a(n-2) + n + 2 with n>1, a(0)=1, a(1)=2.at n=15A210728
- Denominators of Bernoulli numbers which are congruent to 3 (mod 9).at n=34A219543
- Bernoulli denominators with 8 divisors in increasing order (without repetitions).at n=31A219742
- Count of the first 10^n primes which do not contain the digit 0.at n=4A231412
- Triangle read by rows: T(n,k) is the coefficient A_k in the transformation Sum_{k=0..n} (k+1)*x^k = Sum_{k=0..n} A_k*(x+3)^k.at n=23A246798
- Rainbow Squares: a(n) = number of ways to pair the integers 1 to 2n so that the sum of each pair is a square.at n=22A252897
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 278", based on the 5-celled von Neumann neighborhood.at n=27A271097