91573991 has 2 divisors, whose sum is σ = 91573992. Its totient is φ = 91573990.

The previous prime is 91573987. The next prime is 91574011. The reversal of 91573991 is 19937519.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91573991 - 2² = 91573987 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91573931) 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, 45786995 + 45786996.

It is an arithmetic number, because the mean of its divisors is an integer number (45786996).

Almost surely, 2^91573991 is an apocalyptic number.

91573991 is a deficient number, since it is larger than the sum of its proper divisors (1).

91573991 is an equidigital number, since it uses as much as digits as its factorization.

91573991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 76545, while the sum is 44.

The square root of 91573991 is about 9569.4300248238. The cubic root of 91573991 is about 450.7378692828.

The spelling of 91573991 in words is "ninety-one million, five hundred seventy-three thousand, nine hundred ninety-one".