20065 has 4 divisors (see below), whose sum is σ = 24084.
Its totient is φ = 16048.
The previous prime is 20063. The next prime is 20071. The reversal of 20065 is 56002.
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56002 = 2 ⋅28001.
It can be written as a sum of positive squares in 2 ways, for example, as 12321 + 7744 = 111^2 + 88^2
It is a cyclic number.
It is not a de Polignac number, because 20065 - 21 = 20063 is a prime.
It is a Smith number, since the sum of its digits (13) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.
It is a Duffinian number.
It is a plaindrome in base 7.
It is a nialpdrome in base 12.
It is not an unprimeable number, because it can be changed into a prime (20063) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2002 + ... + 2011.
It is an arithmetic number, because the mean of its divisors is an integer number (6021).
220065 is an apocalyptic number.
It is an amenable number.
20065 is a deficient number, since it is larger than the sum of its proper divisors (4019).
20065 is an equidigital number, since it uses as much as digits as its factorization.
20065 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 4018.
The product of its (nonzero) digits is 60, while the sum is 13.
The square root of 20065 is about 141.6509795236.
The cubic root of 20065 is about 27.1735505575.
Adding to 20065 its reverse (56002), we get a palindrome (76067).
Subtracting 20065 from its reverse (56002), we obtain a cube (35937 = 333).
The spelling of 20065 in words is "twenty thousand, sixty-five".