638779911 has 16 divisors (see below), whose sum is σ = 1061868288. Its totient is φ = 331833600.

The previous prime is 638779891. The next prime is 638779927. The reversal of 638779911 is 119977836.

It is not a de Polignac number, because 638779911 - 2⁹ = 638779399 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638771911) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1382410 + ... + 1382871.

It is an arithmetic number, because the mean of its divisors is an integer number (66366768).

Almost surely, 2^638779911 is an apocalyptic number.

638779911 is a deficient number, since it is larger than the sum of its proper divisors (423088377).

638779911 is a wasteful number, since it uses less digits than its factorization.

638779911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2765302.

The product of its digits is 571536, while the sum is 51.

The square root of 638779911 is about 25274.0956514768. The cubic root of 638779911 is about 861.2259022175.

The spelling of 638779911 in words is "six hundred thirty-eight million, seven hundred seventy-nine thousand, nine hundred eleven".