638632385 has 4 divisors (see below), whose sum is σ = 766358868. Its totient is φ = 510905904.

The previous prime is 638632373. The next prime is 638632411. The reversal of 638632385 is 583236836.

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

It can be written as a sum of positive squares in 2 ways, for example, as 417098929 + 221533456 = 20423^2 + 14884^2 .

It is a cyclic number.

It is not a de Polignac number, because 638632385 - 2¹⁰ = 638631361 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63863234 + ... + 63863243.

It is an arithmetic number, because the mean of its divisors is an integer number (191589717).

Almost surely, 2^638632385 is an apocalyptic number.

It is an amenable number.

638632385 is a deficient number, since it is larger than the sum of its proper divisors (127726483).

638632385 is a wasteful number, since it uses less digits than its factorization.

638632385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127726482.

The product of its digits is 622080, while the sum is 44.

The square root of 638632385 is about 25271.1769611152. The cubic root of 638632385 is about 861.1595971712.

The spelling of 638632385 in words is "six hundred thirty-eight million, six hundred thirty-two thousand, three hundred eighty-five".