638630855 has 4 divisors (see below), whose sum is σ = 766357032. Its totient is φ = 510904680.

The previous prime is 638630851. The next prime is 638630873. The reversal of 638630855 is 558036836.

638630855 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.

It is not a de Polignac number, because 638630855 - 2² = 638630851 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 (638630851) 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, 63863081 + ... + 63863090.

It is an arithmetic number, because the mean of its divisors is an integer number (191589258).

Almost surely, 2^638630855 is an apocalyptic number.

638630855 is a deficient number, since it is larger than the sum of its proper divisors (127726177).

638630855 is a wasteful number, since it uses less digits than its factorization.

638630855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127726176.

The product of its (nonzero) digits is 518400, while the sum is 44.

The square root of 638630855 is about 25271.1466894559. The cubic root of 638630855 is about 861.1589094645.

The spelling of 638630855 in words is "six hundred thirty-eight million, six hundred thirty thousand, eight hundred fifty-five".