639549688 has 8 divisors (see below), whose sum is σ = 1199155680. Its totient is φ = 319774840.

The previous prime is 639549683. The next prime is 639549689. The reversal of 639549688 is 886945936.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639549683) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39971848 + ... + 39971863.

It is an arithmetic number, because the mean of its divisors is an integer number (149894460).

Almost surely, 2^639549688 is an apocalyptic number.

It is an amenable number.

639549688 is a deficient number, since it is larger than the sum of its proper divisors (559605992).

639549688 is a wasteful number, since it uses less digits than its factorization.

639549688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79943717 (or 79943713 counting only the distinct ones).

The product of its digits is 11197440, while the sum is 58.

The square root of 639549688 is about 25289.3196428848. The cubic root of 639549688 is about 861.5717102995.

The spelling of 639549688 in words is "six hundred thirty-nine million, five hundred forty-nine thousand, six hundred eighty-eight".