639870858 has 24 divisors (see below), whose sum is σ = 1512422496. Its totient is φ = 193900200.

The previous prime is 639870851. The next prime is 639870863. The reversal of 639870858 is 858078936.

It is a happy number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (639870851) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1615638 + ... + 1616033.

It is an arithmetic number, because the mean of its divisors is an integer number (63017604).

Almost surely, 2^639870858 is an apocalyptic number.

639870858 is an abundant number, since it is smaller than the sum of its proper divisors (872551638).

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

639870858 is a wasteful number, since it uses less digits than its factorization.

639870858 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3231690 (or 3231687 counting only the distinct ones).

The product of its (nonzero) digits is 2903040, while the sum is 54.

The square root of 639870858 is about 25295.6687596909. The cubic root of 639870858 is about 861.7159079459.

The spelling of 639870858 in words is "six hundred thirty-nine million, eight hundred seventy thousand, eight hundred fifty-eight".