5021
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 8
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 5022
- 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
- 5020
- Möbius Function
- -1
- Radical
- 5021
- 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
- 90
- 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
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 673
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes p such that the multiplicative order of 2 modulo p is (p-1)/5.at n=15A001135
- Number of 2-factors in W_4 X P_n.at n=4A003764
- Second (lower) diagonal of partition triangle A047812.at n=12A007045
- Optimal cost of search tree for searching an ordered array of n elements with cost k of probing element k.at n=45A007077
- Coordination sequence for FeS2-Marcasite, S position.at n=37A009954
- Numbers k such that the continued fraction for sqrt(k) has period 19.at n=30A020358
- Smallest nonempty set S containing prime divisors of 9k+8 for each k in S.at n=52A020630
- Numbers with exactly 6 2's in their ternary expansion.at n=31A023704
- Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 12.at n=3A031600
- Number of partitions satisfying (cn(0,5) = 0 and cn(2,5) = cn(3,5)).at n=45A036815
- a(n)=(s(n)+5)/10, where s(n)=n-th base 10 palindrome that starts with 5.at n=24A043084
- Primes with first digit 5.at n=20A045711
- Let f(m) = smallest composite number that takes m steps of "add prime factors to number" to reach a prime and g(m) be the prime that is reached. Sequence gives values of g(m), sorted and duplicates removed.at n=9A050767
- Euclid-Mullin sequence (A000945) with initial value a(1)=8191 instead of a(1)=2.at n=25A051334
- Primes p such that x^5 == 2 (mod p) has five solutions.at n=32A059858
- Primes whose sum of digits is 8.at n=25A062343
- Numbers k such that sigma(k+2) - sigma(k) = prime(k+1) - prime(k).at n=20A067062
- Arithmetic derivative of n*prime(n).at n=45A068981
- Unimodal analog of Fibonacci numbers: a(n+1) = Sum_{k=0..floor(n/2)} A071922(n-k,k).at n=15A072176
- Sum of odd-indexed primes.at n=33A077131