638465831 has 4 divisors (see below), whose sum is σ = 638526312. Its totient is φ = 638405352.

The previous prime is 638465819. The next prime is 638465909. The reversal of 638465831 is 138564836.

638465831 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 638465831 - 2²⁶ = 571356967 is a prime.

It is a super-2 number, since 2×638465831² = 815277234709041122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638465231) 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, 9800 + ... + 37053.

It is an arithmetic number, because the mean of its divisors is an integer number (159631578).

Almost surely, 2^638465831 is an apocalyptic number.

638465831 is a deficient number, since it is larger than the sum of its proper divisors (60481).

638465831 is a wasteful number, since it uses less digits than its factorization.

638465831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60480.

The product of its digits is 414720, while the sum is 44.

The square root of 638465831 is about 25267.8814109929. The cubic root of 638465831 is about 861.0847277839.

The spelling of 638465831 in words is "six hundred thirty-eight million, four hundred sixty-five thousand, eight hundred thirty-one".