638378863 has 4 divisors (see below), whose sum is σ = 651961440. Its totient is φ = 624796288.

The previous prime is 638378833. The next prime is 638378887. The reversal of 638378863 is 368873836.

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

It is a cyclic number.

It is not a de Polignac number, because 638378863 - 2⁵ = 638378831 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 638378863.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638378803) 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, 6791218 + ... + 6791311.

It is an arithmetic number, because the mean of its divisors is an integer number (162990360).

Almost surely, 2^638378863 is an apocalyptic number.

638378863 is a deficient number, since it is larger than the sum of its proper divisors (13582577).

638378863 is a wasteful number, since it uses less digits than its factorization.

638378863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13582576.

The product of its digits is 3483648, while the sum is 52.

The square root of 638378863 is about 25266.1604324836. The cubic root of 638378863 is about 861.0456287367.

The spelling of 638378863 in words is "six hundred thirty-eight million, three hundred seventy-eight thousand, eight hundred sixty-three".