639498618 has 64 divisors (see below), whose sum is σ = 1631923200. Its totient is φ = 183584880.

The previous prime is 639498539. The next prime is 639498619. The reversal of 639498618 is 816894936.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (639498619) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 17046 + ... + 39617.

It is an arithmetic number, because the mean of its divisors is an integer number (25498800).

Almost surely, 2^639498618 is an apocalyptic number.

639498618 is an abundant number, since it is smaller than the sum of its proper divisors (992424582).

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

639498618 is a wasteful number, since it uses less digits than its factorization.

639498618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56704 (or 56698 counting only the distinct ones).

The product of its digits is 2239488, while the sum is 54.

The square root of 639498618 is about 25288.3099079397. The cubic root of 639498618 is about 861.5487766430.

The spelling of 639498618 in words is "six hundred thirty-nine million, four hundred ninety-eight thousand, six hundred eighteen".