309728405 has 32 divisors (see below), whose sum is σ = 451334400. Its totient is φ = 199314432.

The previous prime is 309728401. The next prime is 309728429. The reversal of 309728405 is 504827903.

309728405 = 2303² + 2304² + ... + 2359².

It is a cyclic number.

It is not a de Polignac number, because 309728405 - 2² = 309728401 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (309728401) 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 31 ways as a sum of consecutive naturals, for example, 70349 + ... + 74621.

It is an arithmetic number, because the mean of its divisors is an integer number (14104200).

Almost surely, 2^309728405 is an apocalyptic number.

309728405 is a gapful number since it is divisible by the number (35) formed by its first and last digit.

It is an amenable number.

309728405 is a deficient number, since it is larger than the sum of its proper divisors (141605995).

309728405 is a wasteful number, since it uses less digits than its factorization.

309728405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4413.

The product of its (nonzero) digits is 60480, while the sum is 38.

The square root of 309728405 is about 17599.1023918835. The cubic root of 309728405 is about 676.5922393273.

The spelling of 309728405 in words is "three hundred nine million, seven hundred twenty-eight thousand, four hundred five".