91390991 has 2 divisors, whose sum is σ = 91390992. Its totient is φ = 91390990.

The previous prime is 91390951. The next prime is 91391021. The reversal of 91390991 is 19909319.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91390991 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91390951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45695495 + 45695496.

It is an arithmetic number, because the mean of its divisors is an integer number (45695496).

Almost surely, 2^91390991 is an apocalyptic number.

91390991 is a deficient number, since it is larger than the sum of its proper divisors (1).

91390991 is an equidigital number, since it uses as much as digits as its factorization.

91390991 is an evil number, because the sum of its binary digits is even.

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

The square root of 91390991 is about 9559.8635450513. The cubic root of 91390991 is about 450.4374199382.

The spelling of 91390991 in words is "ninety-one million, three hundred ninety thousand, nine hundred ninety-one".