9981698638 has 4 divisors (see below), whose sum is σ = 14972547960. Its totient is φ = 4990849318.

The previous prime is 9981698603. The next prime is 9981698641. The reversal of 9981698638 is 8368961899.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8368961899 = 72901 ⋅114799.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2495424658 + ... + 2495424661.

It is an arithmetic number, because the mean of its divisors is an integer number (3743136990).

Almost surely, 2^9981698638 is an apocalyptic number.

9981698638 is a deficient number, since it is larger than the sum of its proper divisors (4990849322).

9981698638 is a wasteful number, since it uses less digits than its factorization.

9981698638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4990849321.

The product of its digits is 40310784, while the sum is 67.

The square root of 9981698638 is about 99908.4512841631. The cubic root of 9981698638 is about 2153.1195844589.

The spelling of 9981698638 in words is "nine billion, nine hundred eighty-one million, six hundred ninety-eight thousand, six hundred thirty-eight".