9091991 has 8 divisors (see below), whose sum is σ = 9809424. Its totient is φ = 8394880.

The previous prime is 9091961. The next prime is 9091997. The reversal of 9091991 is 1991909.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9091991 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 (9091997) 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, 4145 + ... + 5946.

It is an arithmetic number, because the mean of its divisors is an integer number (1226178).

Almost surely, 2^9091991 is an apocalyptic number.

9091991 is a deficient number, since it is larger than the sum of its proper divisors (717433).

9091991 is a wasteful number, since it uses less digits than its factorization.

9091991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10161.

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

The square root of 9091991 is about 3015.2928547655. The cubic root of 9091991 is about 208.7146812969.

The spelling of 9091991 in words is "nine million, ninety-one thousand, nine hundred ninety-one".