639528806564 has 12 divisors (see below), whose sum is σ = 1119203837388. Its totient is φ = 319756281600.

The previous prime is 639528806563. The next prime is 639528806599. The reversal of 639528806564 is 465608825936.

It can be written as a sum of positive squares in 2 ways, for example, as 193959206464 + 445569600100 = 440408^2 + 667510^2 .

It is a junction number, because it is equal to n+sod(n) for n = 639528806497 and 639528806506.

It is not an unprimeable number, because it can be changed into a prime (639528806563) 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, 1851497 + ... + 2169584.

It is an arithmetic number, because the mean of its divisors is an integer number (93266986449).

Almost surely, 2^639528806564 is an apocalyptic number.

It is an amenable number.

639528806564 is a deficient number, since it is larger than the sum of its proper divisors (479675030824).

639528806564 is a wasteful number, since it uses less digits than its factorization.

639528806564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4060846 (or 4060844 counting only the distinct ones).

The product of its (nonzero) digits is 74649600, while the sum is 62.

The spelling of 639528806564 in words is "six hundred thirty-nine billion, five hundred twenty-eight million, eight hundred six thousand, five hundred sixty-four".