990990991 has 8 divisors (see below), whose sum is σ = 994262400. Its totient is φ = 987726168.

The previous prime is 990990977. The next prime is 990990997. The reversal of 990990991 is 199099099.

It is a happy number.

990990991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 990990991 - 2⁹ = 990990479 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (990990997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 566380 + ... + 568126.

It is an arithmetic number, because the mean of its divisors is an integer number (124282800).

Almost surely, 2^990990991 is an apocalyptic number.

990990991 is a deficient number, since it is larger than the sum of its proper divisors (3271409).

990990991 is a wasteful number, since it uses less digits than its factorization.

990990991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3293.

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

The square root of 990990991 is about 31480.0093869109. The cubic root of 990990991 is about 996.9879335648.

The spelling of 990990991 in words is "nine hundred ninety million, nine hundred ninety thousand, nine hundred ninety-one".