8521
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 8522
- 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
- 8520
- Möbius Function
- -1
- Radical
- 8521
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 78
- 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
- 1062
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Half-quartan primes: primes of the form p = (x^4 + y^4)/2.at n=7A002646
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 56 ones.at n=11A031824
- Numbers k such that 221*2^k+1 is prime.at n=29A032487
- Let a (resp. b,c,d) be number of primes in the range {2..p} that end in 1 (resp. 3,7,9); sequence gives p such that a=d and b=c.at n=46A038562
- Primes with distinct digits in descending order.at n=39A052014
- Fourth term of strong prime quintets: p(m-2)-p(m-3) > p(m-1)-p(m-2) > p(m)-p(m-1) > p(m+1)-p(m).at n=24A054811
- Primes p for which the period of reciprocal 1/p is (p-1)/12.at n=12A056217
- Primes with 13 as smallest positive primitive root.at n=19A061326
- Primes such that prime(p) +- pi(p) are simultaneously prime.at n=19A065117
- a(1) = 7; a(n) is smallest number > a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=44A074343
- Numbers of the form prime(prime(n)+1), with n satisfying prime(n)+2 = prime(n+1).at n=38A088985
- Primes in which the unit place digit is 1 and the k-th most significant digit is prime (2,3,5,7) if k is prime else is composite (4,6,8,9,0).at n=19A089704
- Numbers k such that k + (largest digit of k)! is a square.at n=44A095927
- Number of solutions to rev(x^2) = rev(x)^2 with n digits, where the rev(x) function reverses the digits of x.at n=10A098701
- Primes from merging of 4 successive digits in decimal expansion of Pi.at n=16A104824
- Primes connected to two primes by the (p+1)/2 and 2p-1 operators.at n=23A109835
- Numbers n such that n, n+1 and n+2 are 1,2,3-almost primes.at n=30A112998
- Primes which are the sum of a twin prime pair + 1.at n=29A118071
- The smallest prime of the form (prime(n+1)^k + prime(n+2)^k)/2 for positive integer k.at n=2A121710
- Smallest prime p such that p^2 equal to the sum of 2n+1 consecutive odd primes, or 1 if such a prime does not exist.at n=43A122654