640838388 has 12 divisors (see below), whose sum is σ = 1495289600. Its totient is φ = 213612792.

The previous prime is 640838371. The next prime is 640838399. The reversal of 640838388 is 883838046.

It is a happy number.

640838388 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26701588 + ... + 26701611.

Almost surely, 2^640838388 is an apocalyptic number.

It is an amenable number.

640838388 is an abundant number, since it is smaller than the sum of its proper divisors (854451212).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640838388 is a wasteful number, since it uses less digits than its factorization.

640838388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53403206 (or 53403204 counting only the distinct ones).

The product of its (nonzero) digits is 884736, while the sum is 48.

The square root of 640838388 is about 25314.7859560376. The cubic root of 640838388 is about 862.1500143556.

The spelling of 640838388 in words is "six hundred forty million, eight hundred thirty-eight thousand, three hundred eighty-eight".