91732078721 has 2 divisors, whose sum is σ = 91732078722. Its totient is φ = 91732078720.

The previous prime is 91732078663. The next prime is 91732078769. The reversal of 91732078721 is 12787023719.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 48791950321 + 42940128400 = 220889^2 + 207220^2 .

It is a cyclic number.

It is not a de Polignac number, because 91732078721 - 2³⁰ = 90658336897 is a prime.

It is not a weakly prime, because it can be changed into another prime (91732078621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45866039360 + 45866039361.

It is an arithmetic number, because the mean of its divisors is an integer number (45866039361).

Almost surely, 2^91732078721 is an apocalyptic number.

It is an amenable number.

91732078721 is a deficient number, since it is larger than the sum of its proper divisors (1).

91732078721 is an equidigital number, since it uses as much as digits as its factorization.

91732078721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 296352, while the sum is 47.

The spelling of 91732078721 in words is "ninety-one billion, seven hundred thirty-two million, seventy-eight thousand, seven hundred twenty-one".