9090990991 has 4 divisors (see below), whose sum is σ = 9096607800. Its totient is φ = 9085374184.

The previous prime is 9090990929. The next prime is 9090991003. The reversal of 9090990991 is 1990990909.

It is a happy number.

9090990991 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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 9090990991 - 2¹¹ = 9090988943 is a prime.

It is a super-2 number, since 2×9090990991² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9090990791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2805976 + ... + 2809213.

It is an arithmetic number, because the mean of its divisors is an integer number (2274151950).

Almost surely, 2^9090990991 is an apocalyptic number.

9090990991 is a deficient number, since it is larger than the sum of its proper divisors (5616809).

9090990991 is a wasteful number, since it uses less digits than its factorization.

9090990991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5616808.

The product of its (nonzero) digits is 531441, while the sum is 55.

The square root of 9090990991 is about 95346.6884112920. The cubic root of 9090990991 is about 2087.0702898646.

The spelling of 9090990991 in words is "nine billion, ninety million, nine hundred ninety thousand, nine hundred ninety-one".