309904728 has 64 divisors (see below), whose sum is σ = 890952960. Its totient is φ = 87993216.

The previous prime is 309904723. The next prime is 309904769. The reversal of 309904728 is 827409903.

It is a super-3 number, since 3×309904728³ (a number of 26 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 309904728.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (309904723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21726 + ... + 33042.

It is an arithmetic number, because the mean of its divisors is an integer number (13921140).

Almost surely, 2^309904728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 309904728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (445476480).

309904728 is an abundant number, since it is smaller than the sum of its proper divisors (581048232).

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

309904728 is a wasteful number, since it uses less digits than its factorization.

309904728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11496 (or 11492 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 42.

The square root of 309904728 is about 17604.1111107605. Note that the first 5 decimals coincide. The cubic root of 309904728 is about 676.7206057072.

The spelling of 309904728 in words is "three hundred nine million, nine hundred four thousand, seven hundred twenty-eight".