91723920571 has 2 divisors, whose sum is σ = 91723920572. Its totient is φ = 91723920570.

The previous prime is 91723920517. The next prime is 91723920593. The reversal of 91723920571 is 17502932719.

Together with previous prime (91723920517) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 91723920571 - 2¹⁵ = 91723887803 is a prime.

It is not a weakly prime, because it can be changed into another prime (91723960571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45861960285 + 45861960286.

It is an arithmetic number, because the mean of its divisors is an integer number (45861960286).

Almost surely, 2^91723920571 is an apocalyptic number.

91723920571 is a deficient number, since it is larger than the sum of its proper divisors (1).

91723920571 is an equidigital number, since it uses as much as digits as its factorization.

91723920571 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 238140, while the sum is 46.

The spelling of 91723920571 in words is "ninety-one billion, seven hundred twenty-three million, nine hundred twenty thousand, five hundred seventy-one".