640328388 has 48 divisors (see below), whose sum is σ = 1712277504. Its totient is φ = 182443680.

The previous prime is 640328383. The next prime is 640328411. The reversal of 640328388 is 883823046.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (640328383) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20443 + ... + 41213.

It is an arithmetic number, because the mean of its divisors is an integer number (35672448).

Almost surely, 2^640328388 is an apocalyptic number.

It is an amenable number.

640328388 is an abundant number, since it is smaller than the sum of its proper divisors (1071949116).

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

640328388 is a wasteful number, since it uses less digits than its factorization.

640328388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21152 (or 21150 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 42.

The square root of 640328388 is about 25304.7107867290. The cubic root of 640328388 is about 861.9212446643.

The spelling of 640328388 in words is "six hundred forty million, three hundred twenty-eight thousand, three hundred eighty-eight".