909099991 has 4 divisors (see below), whose sum is σ = 928442592. Its totient is φ = 889757392.

The previous prime is 909099977. The next prime is 909100013. The reversal of 909099991 is 199990909.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-909099991 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 (909099901) 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, 9671230 + ... + 9671323.

It is an arithmetic number, because the mean of its divisors is an integer number (232110648).

Almost surely, 2^909099991 is an apocalyptic number.

909099991 is a deficient number, since it is larger than the sum of its proper divisors (19342601).

909099991 is a wasteful number, since it uses less digits than its factorization.

909099991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19342600.

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

The square root of 909099991 is about 30151.2850638244. The cubic root of 909099991 is about 968.7325320416.

The spelling of 909099991 in words is "nine hundred nine million, ninety-nine thousand, nine hundred ninety-one".