91920991 has 2 divisors, whose sum is σ = 91920992. Its totient is φ = 91920990.

The previous prime is 91920973. The next prime is 91921013. The reversal of 91920991 is 19902919.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91920991 - 2⁷ = 91920863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91980991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45960495 + 45960496.

It is an arithmetic number, because the mean of its divisors is an integer number (45960496).

Almost surely, 2^91920991 is an apocalyptic number.

91920991 is a deficient number, since it is larger than the sum of its proper divisors (1).

91920991 is an equidigital number, since it uses as much as digits as its factorization.

91920991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13122, while the sum is 40.

The square root of 91920991 is about 9587.5435331476. The cubic root of 91920991 is about 451.3064765116.

The spelling of 91920991 in words is "ninety-one million, nine hundred twenty thousand, nine hundred ninety-one".