128204865 has 24 divisors (see below), whose sum is σ = 222499368. Its totient is φ = 68290560.

The previous prime is 128204851. The next prime is 128204893. The reversal of 128204865 is 568402821.

It can be written as a sum of positive squares in 4 ways, for example, as 12341169 + 115863696 = 3513^2 + 10764^2 .

It is not a de Polignac number, because 128204865 - 2⁹ = 128204353 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 53595 + ... + 55935.

It is an arithmetic number, because the mean of its divisors is an integer number (9270807).

Almost surely, 2^128204865 is an apocalyptic number.

128204865 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

128204865 is a deficient number, since it is larger than the sum of its proper divisors (94294503).

128204865 is a wasteful number, since it uses less digits than its factorization.

128204865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3569 (or 3566 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 36.

The square root of 128204865 is about 11322.7587186162. The cubic root of 128204865 is about 504.2371451078.

The spelling of 128204865 in words is "one hundred twenty-eight million, two hundred four thousand, eight hundred sixty-five".