99128891 has 2 divisors, whose sum is σ = 99128892. Its totient is φ = 99128890.

The previous prime is 99128863. The next prime is 99128893. The reversal of 99128891 is 19882199.

It is a strong prime.

It is an emirp because it is prime and its reverse (19882199) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-99128891 is a prime.

It is a Sophie Germain prime.

Together with 99128893, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (99128893) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49564445 + 49564446.

It is an arithmetic number, because the mean of its divisors is an integer number (49564446).

Almost surely, 2^99128891 is an apocalyptic number.

99128891 is a deficient number, since it is larger than the sum of its proper divisors (1).

99128891 is an equidigital number, since it uses as much as digits as its factorization.

99128891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 93312, while the sum is 47.

The square root of 99128891 is about 9956.3492807354. The cubic root of 99128891 is about 462.8071741742.

The spelling of 99128891 in words is "ninety-nine million, one hundred twenty-eight thousand, eight hundred ninety-one".