638636804 has 18 divisors (see below), whose sum is σ = 1210199130. Its totient is φ = 294755136.

The previous prime is 638636743. The next prime is 638636821. The reversal of 638636804 is 408636836.

It can be written as a sum of positive squares in 3 ways, for example, as 8526400 + 630110404 = 2920^2 + 25102^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 471689 + ... + 473040.

It is an arithmetic number, because the mean of its divisors is an integer number (67233285).

Almost surely, 2^638636804 is an apocalyptic number.

It is an amenable number.

638636804 is a deficient number, since it is larger than the sum of its proper divisors (571562326).

638636804 is a wasteful number, since it uses less digits than its factorization.

638636804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 944759 (or 944744 counting only the distinct ones).

The product of its (nonzero) digits is 497664, while the sum is 44.

The square root of 638636804 is about 25271.2643925863. The cubic root of 638636804 is about 861.1615834237.

The spelling of 638636804 in words is "six hundred thirty-eight million, six hundred thirty-six thousand, eight hundred four".