639308679 has 4 divisors (see below), whose sum is σ = 852411576. Its totient is φ = 426205784.

The previous prime is 639308671. The next prime is 639308701. The reversal of 639308679 is 976803936.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 639308679 - 2³ = 639308671 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639308671) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106551444 + ... + 106551449.

It is an arithmetic number, because the mean of its divisors is an integer number (213102894).

Almost surely, 2^639308679 is an apocalyptic number.

639308679 is a deficient number, since it is larger than the sum of its proper divisors (213102897).

639308679 is a wasteful number, since it uses less digits than its factorization.

639308679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213102896.

The product of its (nonzero) digits is 1469664, while the sum is 51.

The square root of 639308679 is about 25284.5541586163. The cubic root of 639308679 is about 861.4634713156.

The spelling of 639308679 in words is "six hundred thirty-nine million, three hundred eight thousand, six hundred seventy-nine".