7723
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 7724
- Proper Divisor Sum (Aliquot Sum)
- 1
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7722
- Möbius Function
- -1
- Radical
- 7723
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- 52
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 980
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- a(n) = (Sum{1/C(i,j)})*LCM{C(i,j)}, 0 <= j <= i <= n.at n=7A025539
- 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 87.at n=16A031585
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 60 ones.at n=12A031828
- Numbers k such that k-th and (k+1)-st term of A038593 differ by 6.at n=36A038637
- Discriminants of imaginary quadratic fields with class number 9 (negated).at n=29A046006
- Expansion of g.f.: (1-2*x)/(1-3*x+2*x^3).at n=10A052948
- Primes p that have exactly two primitive roots that are not primitive roots mod p^2.at n=39A060518
- Primes with every digit a prime and the sum of the digits a prime.at n=34A062088
- Form a conjugate partition of row with 1+1+1 in first row. all other rows are the union of their parents. a(n) = number of types of piles in the n-th row.at n=25A064480
- Centered 22-gonal numbers.at n=26A069173
- Primes p such that x^3 = 2 has a solution mod p, but x^(3^2) = 2 has no solution mod p.at n=37A070180
- Number of base 4 n-digit numbers with digit sum n.at n=8A071646
- Graded dimension of the cohomology ring of the moduli space of n-pointed stable curves of genus 0 satisfying the associativity equations of physics (also known as the WDVV equations).at n=24A074060
- Primes p such that the number of distinct prime divisors of all composite numbers between p and the next prime is 6.at n=40A075586
- Smaller of a pair of consecutive primes having only prime digits.at n=10A082755
- a(n) = smallest number k such that 2^n + k is a palindrome.at n=29A083463
- Primes which are also prime if their base 19 representation is interpreted as a base 10 number.at n=42A090714
- a(n) is the least k such that (k*prime(n)#)^2 + 1, ((k+1)*prime(n)#)^2 + 1 and ((k+2)*prime(n)#)^2 + 1 are 3 primes, where prime(n)# is the n-th primorial.at n=17A098765
- Primes from merging of 4 successive digits in decimal expansion of (Pi^2).at n=13A104927
- Smallest prime of the form: all sevens followed by prime(n); a(n) > prime(n); or 0 if no such prime exists.at n=8A113889