638253018 has 24 divisors (see below), whose sum is σ = 1489257588. Its totient is φ = 196385472.

The previous prime is 638253001. The next prime is 638253019. The reversal of 638253018 is 810352836.

638253018 is a `hidden beast` number, since 638 + 2 + 5 + 3 + 0 + 18 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 529322049 + 108930969 = 23007^2 + 10437^2 .

It is a super-2 number, since 2×638253018² = 814733829972216648, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (638253019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1363555 + ... + 1364022.

Almost surely, 2^638253018 is an apocalyptic number.

638253018 is an abundant number, since it is smaller than the sum of its proper divisors (851004570).

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

638253018 is a wasteful number, since it uses less digits than its factorization.

638253018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2727598 (or 2727595 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 638253018 is about 25263.6699234296. The cubic root of 638253018 is about 860.9890450920.

The spelling of 638253018 in words is "six hundred thirty-eight million, two hundred fifty-three thousand, eighteen".