638993138 has 8 divisors (see below), whose sum is σ = 1095416832. Its totient is φ = 273854196.

The previous prime is 638993101. The next prime is 638993143. The reversal of 638993138 is 831399836.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×638993138² = 816624460822174088, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22821170 + ... + 22821197.

It is an arithmetic number, because the mean of its divisors is an integer number (136927104).

Almost surely, 2^638993138 is an apocalyptic number.

638993138 is a deficient number, since it is larger than the sum of its proper divisors (456423694).

638993138 is a wasteful number, since it uses less digits than its factorization.

638993138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45642376.

The product of its digits is 839808, while the sum is 50.

The square root of 638993138 is about 25278.3135909024. The cubic root of 638993138 is about 861.3217183106.

The spelling of 638993138 in words is "six hundred thirty-eight million, nine hundred ninety-three thousand, one hundred thirty-eight".