638997258 has 32 divisors (see below), whose sum is σ = 1376118720. Its totient is φ = 197070080.

The previous prime is 638997193. The next prime is 638997269. The reversal of 638997258 is 852799836.

It is a junction number, because it is equal to n+sod(n) for n = 638997198 and 638997207.

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, 47073 + ... + 59108.

It is an arithmetic number, because the mean of its divisors is an integer number (43003710).

Almost surely, 2^638997258 is an apocalyptic number.

638997258 is an abundant number, since it is smaller than the sum of its proper divisors (737121462).

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

638997258 is a wasteful number, since it uses less digits than its factorization.

638997258 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106262.

The product of its digits is 6531840, while the sum is 57.

The square root of 638997258 is about 25278.3950835491. The cubic root of 638997258 is about 861.3235694718.

The spelling of 638997258 in words is "six hundred thirty-eight million, nine hundred ninety-seven thousand, two hundred fifty-eight".