639298388021 has 8 divisors (see below), whose sum is σ = 640594987224. Its totient is φ = 638002632960.

The previous prime is 639298387997. The next prime is 639298388083. The reversal of 639298388021 is 120883892936.

It can be written as a sum of positive squares in 4 ways, for example, as 129538087396 + 509760300625 = 359914^2 + 713975^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 639298388021 - 2²⁶ = 639231279157 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 (639298388321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1316351 + ... + 1735331.

It is an arithmetic number, because the mean of its divisors is an integer number (80074373403).

Almost surely, 2^639298388021 is an apocalyptic number.

It is an amenable number.

639298388021 is a deficient number, since it is larger than the sum of its proper divisors (1296599203).

639298388021 is a wasteful number, since it uses less digits than its factorization.

639298388021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 422071.

The product of its (nonzero) digits is 8957952, while the sum is 59.

The spelling of 639298388021 in words is "six hundred thirty-nine billion, two hundred ninety-eight million, three hundred eighty-eight thousand, twenty-one".