990910091 has 4 divisors (see below), whose sum is σ = 1000721184. Its totient is φ = 981099000.

The previous prime is 990910087. The next prime is 990910121. The reversal of 990910091 is 190019099.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 990910091 - 2² = 990910087 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (990910051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4905395 + ... + 4905596.

It is an arithmetic number, because the mean of its divisors is an integer number (250180296).

Almost surely, 2^990910091 is an apocalyptic number.

990910091 is a deficient number, since it is larger than the sum of its proper divisors (9811093).

990910091 is a wasteful number, since it uses less digits than its factorization.

990910091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9811092.

The product of its (nonzero) digits is 6561, while the sum is 38.

The square root of 990910091 is about 31478.7244182480. The cubic root of 990910091 is about 996.9608029722.

The spelling of 990910091 in words is "nine hundred ninety million, nine hundred ten thousand, ninety-one".