638966255555 has 4 divisors (see below), whose sum is σ = 766759506672. Its totient is φ = 511173004440.

The previous prime is 638966255549. The next prime is 638966255569. The reversal of 638966255555 is 555552669836.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-638966255555 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 638966255491 and 638966255500.

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, 63896625551 + ... + 63896625560.

It is an arithmetic number, because the mean of its divisors is an integer number (191689876668).

Almost surely, 2^638966255555 is an apocalyptic number.

638966255555 is a deficient number, since it is larger than the sum of its proper divisors (127793251117).

638966255555 is a wasteful number, since it uses less digits than its factorization.

638966255555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127793251116.

The product of its digits is 291600000, while the sum is 65.

The spelling of 638966255555 in words is "six hundred thirty-eight billion, nine hundred sixty-six million, two hundred fifty-five thousand, five hundred fifty-five".