638713898 has 4 divisors (see below), whose sum is σ = 958070850. Its totient is φ = 319356948.

The previous prime is 638713897. The next prime is 638713903. The reversal of 638713898 is 898317836.

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., 349951849 + 288762049 = 18707^2 + 16993^2 .

It is not an unprimeable number, because it can be changed into a prime (638713891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159678473 + ... + 159678476.

Almost surely, 2^638713898 is an apocalyptic number.

638713898 is a deficient number, since it is larger than the sum of its proper divisors (319356952).

638713898 is a wasteful number, since it uses less digits than its factorization.

638713898 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319356951.

The product of its digits is 1741824, while the sum is 53.

The square root of 638713898 is about 25272.7896758549. The cubic root of 638713898 is about 861.1962341670.

The spelling of 638713898 in words is "six hundred thirty-eight million, seven hundred thirteen thousand, eight hundred ninety-eight".