9391991 has 4 divisors (see below), whose sum is σ = 10733712. Its totient is φ = 8050272.

The previous prime is 9391979. The next prime is 9392003. The reversal of 9391991 is 1991939.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1991939 = 191 ⋅10429.

It is an interprime number because it is at equal distance from previous prime (9391979) and next prime (9392003).

It is a cyclic number.

It is not a de Polignac number, because 9391991 - 2⁶ = 9391927 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 (9391691) 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, 670850 + ... + 670863.

It is an arithmetic number, because the mean of its divisors is an integer number (2683428).

Almost surely, 2^9391991 is an apocalyptic number.

9391991 is a deficient number, since it is larger than the sum of its proper divisors (1341721).

9391991 is a wasteful number, since it uses less digits than its factorization.

9391991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1341720.

The product of its digits is 19683, while the sum is 41.

The square root of 9391991 is about 3064.6355411370. The cubic root of 9391991 is about 210.9854740193.

The spelling of 9391991 in words is "nine million, three hundred ninety-one thousand, nine hundred ninety-one".