638666338 has 4 divisors (see below), whose sum is σ = 957999510. Its totient is φ = 319333168.

The previous prime is 638666297. The next prime is 638666351. The reversal of 638666338 is 833666836.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 425885769 + 212780569 = 20637^2 + 14587^2 .

It is a junction number, because it is equal to n+sod(n) for n = 638666291 and 638666300.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159666583 + ... + 159666586.

Almost surely, 2^638666338 is an apocalyptic number.

638666338 is a deficient number, since it is larger than the sum of its proper divisors (319333172).

638666338 is a wasteful number, since it uses less digits than its factorization.

638666338 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319333171.

The product of its digits is 2239488, while the sum is 49.

The square root of 638666338 is about 25271.8487254099. The cubic root of 638666338 is about 861.1748581332.

The spelling of 638666338 in words is "six hundred thirty-eight million, six hundred sixty-six thousand, three hundred thirty-eight".