99911999 has 12 divisors (see below), whose sum is σ = 110861352. Its totient is φ = 89968560.

The previous prime is 99911993. The next prime is 99912017.

99911999 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 99911999 - 2⁴ = 99911983 is a prime.

It is a Duffinian number.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99911993) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9089 + ... + 16805.

It is an arithmetic number, because the mean of its divisors is an integer number (9238446).

Almost surely, 2^99911999 is an apocalyptic number.

99911999 is a deficient number, since it is larger than the sum of its proper divisors (10949353).

99911999 is a wasteful number, since it uses less digits than its factorization.

99911999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7846 (or 7835 counting only the distinct ones).

The product of its digits is 531441, while the sum is 56.

The square root of 99911999 is about 9995.5989815518. The cubic root of 99911999 is about 464.0226885829.

The spelling of 99911999 in words is "ninety-nine million, nine hundred eleven thousand, nine hundred ninety-nine".