128765309 has 2 divisors, whose sum is σ = 128765310. Its totient is φ = 128765308.

The previous prime is 128765279. The next prime is 128765311. The reversal of 128765309 is 903567821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 91738084 + 37027225 = 9578^2 + 6085^2 .

It is a cyclic number.

It is not a de Polignac number, because 128765309 - 2⁸ = 128765053 is a prime.

Together with 128765311, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128765369) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64382654 + 64382655.

It is an arithmetic number, because the mean of its divisors is an integer number (64382655).

Almost surely, 2^128765309 is an apocalyptic number.

It is an amenable number.

128765309 is a deficient number, since it is larger than the sum of its proper divisors (1).

128765309 is an equidigital number, since it uses as much as digits as its factorization.

128765309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 90720, while the sum is 41.

The square root of 128765309 is about 11347.4802929990. The cubic root of 128765309 is about 504.9708299329.

The spelling of 128765309 in words is "one hundred twenty-eight million, seven hundred sixty-five thousand, three hundred nine".