639788647 has 4 divisors (see below), whose sum is σ = 641972520. Its totient is φ = 637604776.

The previous prime is 639788627. The next prime is 639788657. The reversal of 639788647 is 746887936.

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 639788647 - 2¹¹ = 639786599 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 639788591 and 639788600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639788627) 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, 1091497 + ... + 1092082.

It is an arithmetic number, because the mean of its divisors is an integer number (160493130).

Almost surely, 2^639788647 is an apocalyptic number.

639788647 is a deficient number, since it is larger than the sum of its proper divisors (2183873).

639788647 is a wasteful number, since it uses less digits than its factorization.

639788647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2183872.

The product of its digits is 12192768, while the sum is 58.

The square root of 639788647 is about 25294.0437059795. The cubic root of 639788647 is about 861.6790017693.

The spelling of 639788647 in words is "six hundred thirty-nine million, seven hundred eighty-eight thousand, six hundred forty-seven".