20505223 has 4 divisors (see below), whose sum is σ = 20892168. Its totient is φ = 20118280.

The previous prime is 20505217. The next prime is 20505227. The reversal of 20505223 is 32250502.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20505223 - 2¹³ = 20497031 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20505223.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20505227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 193393 + ... + 193498.

It is an arithmetic number, because the mean of its divisors is an integer number (5223042).

Almost surely, 2^20505223 is an apocalyptic number.

20505223 is a deficient number, since it is larger than the sum of its proper divisors (386945).

20505223 is an equidigital number, since it uses as much as digits as its factorization.

20505223 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 386944.

The product of its (nonzero) digits is 600, while the sum is 19.

The square root of 20505223 is about 4528.2693161958. The cubic root of 20505223 is about 273.7084249811.

Adding to 20505223 its reverse (32250502), we get a palindrome (52755725).

The spelling of 20505223 in words is "twenty million, five hundred five thousand, two hundred twenty-three".