91085509 has 2 divisors, whose sum is σ = 91085510. Its totient is φ = 91085508.

The previous prime is 91085503. The next prime is 91085521. The reversal of 91085509 is 90558019.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74909025 + 16176484 = 8655^2 + 4022^2 .

It is a cyclic number.

It is not a de Polignac number, because 91085509 - 2⁷ = 91085381 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91085503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45542754 + 45542755.

It is an arithmetic number, because the mean of its divisors is an integer number (45542755).

Almost surely, 2^91085509 is an apocalyptic number.

It is an amenable number.

91085509 is a deficient number, since it is larger than the sum of its proper divisors (1).

91085509 is an equidigital number, since it uses as much as digits as its factorization.

91085509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16200, while the sum is 37.

The square root of 91085509 is about 9543.8728512067. The cubic root of 91085509 is about 449.9349848459.

The spelling of 91085509 in words is "ninety-one million, eighty-five thousand, five hundred nine".