643855328 has 24 divisors (see below), whose sum is σ = 1284959088. Its totient is φ = 317516544.

The previous prime is 643855321. The next prime is 643855343. The reversal of 643855328 is 823558346.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643855321) 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 3 ways as a sum of consecutive naturals, for example, 135476 + ... + 140147.

It is an arithmetic number, because the mean of its divisors is an integer number (53539962).

Almost surely, 2^643855328 is an apocalyptic number.

It is an amenable number.

643855328 is a deficient number, since it is larger than the sum of its proper divisors (641103760).

643855328 is a wasteful number, since it uses less digits than its factorization.

643855328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 275706 (or 275698 counting only the distinct ones).

The product of its digits is 691200, while the sum is 44.

The square root of 643855328 is about 25374.3044830789. The cubic root of 643855328 is about 863.5008405051.

The spelling of 643855328 in words is "six hundred forty-three million, eight hundred fifty-five thousand, three hundred twenty-eight".