1638399998 has 8 divisors (see below), whose sum is σ = 2457993720. Its totient is φ = 819068760.

The previous prime is 1638399989. The next prime is 1638400013. The reversal of 1638399998 is 8999938361.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 49193 + ... + 75476.

It is an arithmetic number, because the mean of its divisors is an integer number (307249215).

Almost surely, 2^1638399998 is an apocalyptic number.

1638399998 is a deficient number, since it is larger than the sum of its proper divisors (819593722).

1638399998 is a wasteful number, since it uses less digits than its factorization.

1638399998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131242.

The product of its digits is 22674816, while the sum is 65.

The square root of 1638399998 is about 40477.1540254500. The cubic root of 1638399998 is about 1178.8900790852.

The spelling of 1638399998 in words is "one billion, six hundred thirty-eight million, three hundred ninety-nine thousand, nine hundred ninety-eight".