638712863 has 4 divisors (see below), whose sum is σ = 638768640. Its totient is φ = 638657088.

The previous prime is 638712821. The next prime is 638712889. The reversal of 638712863 is 368217836.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 638712863 - 2⁶ = 638712799 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 (638714863) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3743 + ... + 35936.

It is an arithmetic number, because the mean of its divisors is an integer number (159692160).

Almost surely, 2^638712863 is an apocalyptic number.

638712863 is a deficient number, since it is larger than the sum of its proper divisors (55777).

638712863 is a wasteful number, since it uses less digits than its factorization.

638712863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55776.

The product of its digits is 290304, while the sum is 44.

The square root of 638712863 is about 25272.7691992785. The cubic root of 638712863 is about 861.1957689933.

The spelling of 638712863 in words is "six hundred thirty-eight million, seven hundred twelve thousand, eight hundred sixty-three".