639427328164 has 27 divisors (see below), whose sum is σ = 1134743727747. Its totient is φ = 315276450624.

The previous prime is 639427328161. The next prime is 639427328171. The reversal of 639427328164 is 461823724936.

The square root of 639427328164 is 799642.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 345793393764 + 293633934400 = 588042^2 + 541880^2 .

It is a super-2 number, since 2×639427328164² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639427328161) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 116744994 + ... + 116750470.

Almost surely, 2^639427328164 is an apocalyptic number.

639427328164 is the 799642-nd square number.

It is an amenable number.

639427328164 is a deficient number, since it is larger than the sum of its proper divisors (495316399583).

639427328164 is an frugal number, since it uses more digits than its factorization.

639427328164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11104 (or 5552 counting only the distinct ones).

The product of its digits is 10450944, while the sum is 55.

The spelling of 639427328164 in words is "six hundred thirty-nine billion, four hundred twenty-seven million, three hundred twenty-eight thousand, one hundred sixty-four".