638783879 has 4 divisors (see below), whose sum is σ = 638946840. Its totient is φ = 638620920.

The previous prime is 638783839. The next prime is 638783881. The reversal of 638783879 is 978387836.

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 638783879 - 2²⁴ = 622006663 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 (638783839) 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, 75452 + ... + 83489.

It is an arithmetic number, because the mean of its divisors is an integer number (159736710).

Almost surely, 2^638783879 is an apocalyptic number.

638783879 is a deficient number, since it is larger than the sum of its proper divisors (162961).

638783879 is a wasteful number, since it uses less digits than its factorization.

638783879 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162960.

The product of its digits is 12192768, while the sum is 59.

The square root of 638783879 is about 25274.1741507017. The cubic root of 638783879 is about 861.2276854803.

The spelling of 638783879 in words is "six hundred thirty-eight million, seven hundred eighty-three thousand, eight hundred seventy-nine".