91009913 has 2 divisors, whose sum is σ = 91009914. Its totient is φ = 91009912.

The previous prime is 91009889. The next prime is 91009931. The reversal of 91009913 is 31990019.

Together with next prime (91009931) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 83320384 + 7689529 = 9128^2 + 2773^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91009913 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 91009913.

It is not a weakly prime, because it can be changed into another prime (91009213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45504956 + 45504957.

It is an arithmetic number, because the mean of its divisors is an integer number (45504957).

Almost surely, 2^91009913 is an apocalyptic number.

It is an amenable number.

91009913 is a deficient number, since it is larger than the sum of its proper divisors (1).

91009913 is an equidigital number, since it uses as much as digits as its factorization.

91009913 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2187, while the sum is 32.

The square root of 91009913 is about 9539.9115823995. The cubic root of 91009913 is about 449.8104765695.

The spelling of 91009913 in words is "ninety-one million, nine thousand, nine hundred thirteen".