309328720 has 20 divisors (see below), whose sum is σ = 719189460. Its totient is φ = 123731456.

The previous prime is 309328717. The next prime is 309328727. The reversal of 309328720 is 27823903.

It can be written as a sum of positive squares in 2 ways, for example, as 98962704 + 210366016 = 9948^2 + 14504^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (309328727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1933225 + ... + 1933384.

It is an arithmetic number, because the mean of its divisors is an integer number (35959473).

Almost surely, 2^309328720 is an apocalyptic number.

It is an amenable number.

309328720 is an abundant number, since it is smaller than the sum of its proper divisors (409860740).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

309328720 is a wasteful number, since it uses less digits than its factorization.

309328720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3866622 (or 3866616 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 34.

The square root of 309328720 is about 17587.7434595800. The cubic root of 309328720 is about 676.3010808264.

It can be divided in two parts, 3093 and 28720, that added together give a palindrome (31813).

The spelling of 309328720 in words is "three hundred nine million, three hundred twenty-eight thousand, seven hundred twenty".