91505681 has 2 divisors, whose sum is σ = 91505682. Its totient is φ = 91505680.

The previous prime is 91505647. The next prime is 91505693. The reversal of 91505681 is 18650519.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 86192656 + 5313025 = 9284^2 + 2305^2 .

It is a cyclic number.

It is not a de Polignac number, because 91505681 - 2²² = 87311377 is a prime.

It is a super-2 number, since 2×91505681² = 16746579310547522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (91505641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45752840 + 45752841.

It is an arithmetic number, because the mean of its divisors is an integer number (45752841).

Almost surely, 2^91505681 is an apocalyptic number.

It is an amenable number.

91505681 is a deficient number, since it is larger than the sum of its proper divisors (1).

91505681 is an equidigital number, since it uses as much as digits as its factorization.

91505681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10800, while the sum is 35.

The square root of 91505681 is about 9565.8601808724. The cubic root of 91505681 is about 450.6257648063.

The spelling of 91505681 in words is "ninety-one million, five hundred five thousand, six hundred eighty-one".