9099991 has 4 divisors (see below), whose sum is σ = 9321984. Its totient is φ = 8878000.

The previous prime is 9099989. The next prime is 9100009. The reversal of 9099991 is 1999909.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1999909 = 587 ⋅3407.

It is a cyclic number.

It is not a de Polignac number, because 9099991 - 2¹ = 9099989 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9099901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110935 + ... + 111016.

It is an arithmetic number, because the mean of its divisors is an integer number (2330496).

Almost surely, 2^9099991 is an apocalyptic number.

9099991 is a deficient number, since it is larger than the sum of its proper divisors (221993).

9099991 is a wasteful number, since it uses less digits than its factorization.

9099991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221992.

The product of its (nonzero) digits is 59049, while the sum is 46.

The square root of 9099991 is about 3016.6191340638. The cubic root of 9099991 is about 208.7758790391.

It can be divided in two parts, 9099 and 991, that multiplied together give a palindrome (9017109).

The spelling of 9099991 in words is "nine million, ninety-nine thousand, nine hundred ninety-one".