638523858 has 32 divisors (see below), whose sum is σ = 1490540544. Its totient is φ = 178553232.

The previous prime is 638523841. The next prime is 638523863. The reversal of 638523858 is 858325836.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an alternating number because its digits alternate between even and odd.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 159760 + ... + 163707.

It is an arithmetic number, because the mean of its divisors is an integer number (46579392).

Almost surely, 2^638523858 is an apocalyptic number.

638523858 is an abundant number, since it is smaller than the sum of its proper divisors (852016686).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638523858 is a wasteful number, since it uses less digits than its factorization.

638523858 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 323526.

The product of its digits is 1382400, while the sum is 48.

The square root of 638523858 is about 25269.0296212577. The cubic root of 638523858 is about 861.1108135703.

The spelling of 638523858 in words is "six hundred thirty-eight million, five hundred twenty-three thousand, eight hundred fifty-eight".