99000991 has 2 divisors, whose sum is σ = 99000992.
Its totient is φ = 99000990.
The previous prime is 99000977. The next prime is 99001031. The reversal of 99000991 is 19900099.
It is a weak prime.
It is a cyclic number.
It is not a de Polignac number, because 99000991 - 29 = 99000479 is a prime.
It is a self number, because there is not a number n which added to its sum of digits gives 99000991.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (99000791) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49500495 + 49500496.
It is an arithmetic number, because the mean of its divisors is an integer number (49500496).
Almost surely, 299000991 is an apocalyptic number.
99000991 is a deficient number, since it is larger than the sum of its proper divisors (1).
99000991 is an equidigital number, since it uses as much as digits as its factorization.
99000991 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 6561, while the sum is 37.
The square root of 99000991 is about 9949.9241705653.
The cubic root of 99000991 is about 462.6080444924.
The spelling of 99000991 in words is "ninety-nine million, nine hundred ninety-one", and thus it is an aban number.