638795532565 has 4 divisors (see below), whose sum is σ = 766554639084. Its totient is φ = 511036426048.

The previous prime is 638795532547. The next prime is 638795532581. The reversal of 638795532565 is 565235597836.

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 118386229329 + 520409303236 = 344073^2 + 721394^2 .

It is a cyclic number.

It is not a de Polignac number, because 638795532565 - 2⁵ = 638795532533 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 638795532497 and 638795532506.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63879553252 + ... + 63879553261.

It is an arithmetic number, because the mean of its divisors is an integer number (191638659771).

Almost surely, 2^638795532565 is an apocalyptic number.

It is an amenable number.

638795532565 is a deficient number, since it is larger than the sum of its proper divisors (127759106519).

638795532565 is a wasteful number, since it uses less digits than its factorization.

638795532565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127759106518.

The product of its digits is 204120000, while the sum is 64.

The spelling of 638795532565 in words is "six hundred thirty-eight billion, seven hundred ninety-five million, five hundred thirty-two thousand, five hundred sixty-five".