639604247 has 4 divisors (see below), whose sum is σ = 653212896. Its totient is φ = 625995600.

The previous prime is 639604213. The next prime is 639604271. The reversal of 639604247 is 742406936.

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 639604247 - 2¹² = 639600151 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639604547) 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, 6804254 + ... + 6804347.

It is an arithmetic number, because the mean of its divisors is an integer number (163303224).

Almost surely, 2^639604247 is an apocalyptic number.

639604247 is a deficient number, since it is larger than the sum of its proper divisors (13608649).

639604247 is a wasteful number, since it uses less digits than its factorization.

639604247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13608648.

The product of its (nonzero) digits is 217728, while the sum is 41.

The square root of 639604247 is about 25290.3983163571. The cubic root of 639604247 is about 861.5962093885.

The spelling of 639604247 in words is "six hundred thirty-nine million, six hundred four thousand, two hundred forty-seven".