998999999 has 2 divisors, whose sum is σ = 999000000. Its totient is φ = 998999998.

The previous prime is 998999971. The next prime is 999000011. The reversal of 998999999 is 999999899.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 998999999 - 2¹² = 998995903 is a prime.

It is a Chen prime.

998999999 is a modest number, since divided by 99999 gives 9989 as remainder.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (998990999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499499999 + 499500000.

It is an arithmetic number, because the mean of its divisors is an integer number (499500000).

Almost surely, 2^998999999 is an apocalyptic number.

998999999 is a deficient number, since it is larger than the sum of its proper divisors (1).

998999999 is an equidigital number, since it uses as much as digits as its factorization.

998999999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 344373768, while the sum is 80.

The square root of 998999999 is about 31606.9612427389. The cubic root of 998999999 is about 999.6665551602. Note that the first 3 decimals are identical.

The spelling of 998999999 in words is "nine hundred ninety-eight million, nine hundred ninety-nine thousand, nine hundred ninety-nine".