639879390 has 48 divisors (see below), whose sum is σ = 1669108896. Its totient is φ = 170078400.

The previous prime is 639879353. The next prime is 639879391. The reversal of 639879390 is 93978936.

639879390 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639879391) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16560 + ... + 39420.

It is an arithmetic number, because the mean of its divisors is an integer number (34773102).

Almost surely, 2^639879390 is an apocalyptic number.

639879390 is an abundant number, since it is smaller than the sum of its proper divisors (1029229506).

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

639879390 is a wasteful number, since it uses less digits than its factorization.

639879390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23185 (or 23182 counting only the distinct ones).

The product of its (nonzero) digits is 2204496, while the sum is 54.

The square root of 639879390 is about 25295.8374046008. The cubic root of 639879390 is about 861.7197379518.

The spelling of 639879390 in words is "six hundred thirty-nine million, eight hundred seventy-nine thousand, three hundred ninety".