320821906 has 12 divisors (see below), whose sum is σ = 491696478. Its totient is φ = 156995792.

The previous prime is 320821903. The next prime is 320821937. The reversal of 320821906 is 609128023.

320821906 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 179426025 + 141395881 = 13395^2 + 11891^2 .

It is not an unprimeable number, because it can be changed into a prime (320821903) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 31891 + ... + 40726.

Almost surely, 2^320821906 is an apocalyptic number.

320821906 is a deficient number, since it is larger than the sum of its proper divisors (170874572).

320821906 is an equidigital number, since it uses as much as digits as its factorization.

320821906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72713 (or 72666 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 320821906 is about 17911.5020587331. The cubic root of 320821906 is about 684.5754778101.

Adding to 320821906 its reverse (609128023), we get a palindrome (929949929).

The spelling of 320821906 in words is "three hundred twenty million, eight hundred twenty-one thousand, nine hundred six".