639725618 has 8 divisors (see below), whose sum is σ = 1096672512. Its totient is φ = 274168116.

The previous prime is 639725609. The next prime is 639725621. The reversal of 639725618 is 816527936.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22847330 + ... + 22847357.

It is an arithmetic number, because the mean of its divisors is an integer number (137084064).

Almost surely, 2^639725618 is an apocalyptic number.

639725618 is a deficient number, since it is larger than the sum of its proper divisors (456946894).

639725618 is a wasteful number, since it uses less digits than its factorization.

639725618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45694696.

The product of its digits is 544320, while the sum is 47.

The square root of 639725618 is about 25292.7977495571. The cubic root of 639725618 is about 861.6507046383.

The spelling of 639725618 in words is "six hundred thirty-nine million, seven hundred twenty-five thousand, six hundred eighteen".