639300972865 has 4 divisors (see below), whose sum is σ = 767161167444. Its totient is φ = 511440778288.

The previous prime is 639300972853. The next prime is 639300972887. The reversal of 639300972865 is 568279003936.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 203320729921 + 435980242944 = 450911^2 + 660288^2 .

It is a cyclic number.

It is not a de Polignac number, because 639300972865 - 2¹⁷ = 639300841793 is a prime.

It is a super-2 number, since 2×639300972865² (a number of 24 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63930097282 + ... + 63930097291.

It is an arithmetic number, because the mean of its divisors is an integer number (191790291861).

Almost surely, 2^639300972865 is an apocalyptic number.

It is an amenable number.

639300972865 is a deficient number, since it is larger than the sum of its proper divisors (127860194579).

639300972865 is a wasteful number, since it uses less digits than its factorization.

639300972865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127860194578.

The product of its (nonzero) digits is 14696640, while the sum is 58.

The spelling of 639300972865 in words is "six hundred thirty-nine billion, three hundred million, nine hundred seventy-two thousand, eight hundred sixty-five".