638815005 has 20 divisors (see below), whose sum is σ = 1145135772. Its totient is φ = 340701120.

The previous prime is 638814977. The next prime is 638815019. The reversal of 638815005 is 500518836.

638815005 is a `hidden beast` number, since 638 + 8 + 15 + 0 + 0 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 102151449 + 536663556 = 10107^2 + 23166^2 .

It is not a de Polignac number, because 638815005 - 2⁸ = 638814749 is a prime.

It is a super-2 number, since 2×638815005² = 816169221226300050, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 788256 + ... + 789065.

Almost surely, 2^638815005 is an apocalyptic number.

It is an amenable number.

638815005 is a deficient number, since it is larger than the sum of its proper divisors (506320767).

638815005 is a wasteful number, since it uses less digits than its factorization.

638815005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1577338 (or 1577329 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The square root of 638815005 is about 25274.7899101061. The cubic root of 638815005 is about 861.2416735903.

It can be divided in two parts, 63881 and 5005, that added together give a palindrome (68886).

The spelling of 638815005 in words is "six hundred thirty-eight million, eight hundred fifteen thousand, five".