99999991121 has 4 divisors (see below), whose sum is σ = 100012148544. Its totient is φ = 99987833700.

The previous prime is 99999991111. The next prime is 99999991129. The reversal of 99999991121 is 12119999999.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-99999991121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99999991129) 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, 6066365 + ... + 6082826.

It is an arithmetic number, because the mean of its divisors is an integer number (25003037136).

Almost surely, 2^99999991121 is an apocalyptic number.

It is an amenable number.

99999991121 is a deficient number, since it is larger than the sum of its proper divisors (12157423).

99999991121 is a wasteful number, since it uses less digits than its factorization.

99999991121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12157422.

The product of its digits is 9565938, while the sum is 68.

The spelling of 99999991121 in words is "ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-one thousand, one hundred twenty-one".