9998999999 has 4 divisors (see below), whose sum is σ = 10004004000. Its totient is φ = 9993996000.

The previous prime is 9998999977. The next prime is 9999000001. The reversal of 9998999999 is 9999998999.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9999998999 = 439 ⋅22779041.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9998999999 is a prime.

It is a Duffinian number.

9998999999 is a modest number, since divided by 99999 gives 99989 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9998999909) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2499002 + ... + 2502999.

It is an arithmetic number, because the mean of its divisors is an integer number (2501001000).

Almost surely, 2^9998999999 is an apocalyptic number.

9998999999 is a deficient number, since it is larger than the sum of its proper divisors (5004001).

9998999999 is a wasteful number, since it uses less digits than its factorization.

9998999999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5004000.

The product of its digits is 3099363912, while the sum is 89.

The square root of 9998999999 is about 99994.9998699935. Note that the first 3 decimals coincide. The cubic root of 9998999999 is about 2154.3628730764.

The spelling of 9998999999 in words is "nine billion, nine hundred ninety-eight million, nine hundred ninety-nine thousand, nine hundred ninety-nine".