928128639 has 4 divisors (see below), whose sum is σ = 1237504856. Its totient is φ = 618752424.

The previous prime is 928128629. The next prime is 928128647. The reversal of 928128639 is 936821829.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 928128639 - 2¹³ = 928120447 is a prime.

It is a super-2 number, since 2×928128639² = 1722845541063984642, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (928128629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 154688104 + ... + 154688109.

It is an arithmetic number, because the mean of its divisors is an integer number (309376214).

Almost surely, 2^928128639 is an apocalyptic number.

928128639 is a deficient number, since it is larger than the sum of its proper divisors (309376217).

928128639 is a wasteful number, since it uses less digits than its factorization.

928128639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 309376216.

The product of its digits is 373248, while the sum is 48.

The square root of 928128639 is about 30465.2037413177. The cubic root of 928128639 is about 975.4448599792. Note that the first 3 decimals are identical.

The spelling of 928128639 in words is "nine hundred twenty-eight million, one hundred twenty-eight thousand, six hundred thirty-nine".