309728897 has 2 divisors, whose sum is σ = 309728898. Its totient is φ = 309728896.

The previous prime is 309728863. The next prime is 309728917. The reversal of 309728897 is 798827903.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 309724801 + 4096 = 17599^2 + 64^2 .

It is an emirp because it is prime and its reverse (798827903) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 309728897 - 2²⁶ = 242620033 is a prime.

It is not a weakly prime, because it can be changed into another prime (309721897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 154864448 + 154864449.

It is an arithmetic number, because the mean of its divisors is an integer number (154864449).

Almost surely, 2^309728897 is an apocalyptic number.

It is an amenable number.

309728897 is a deficient number, since it is larger than the sum of its proper divisors (1).

309728897 is an equidigital number, since it uses as much as digits as its factorization.

309728897 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1524096, while the sum is 53.

The square root of 309728897 is about 17599.1163698636. The cubic root of 309728897 is about 676.5925975801.

The spelling of 309728897 in words is "three hundred nine million, seven hundred twenty-eight thousand, eight hundred ninety-seven".