91089209 has 2 divisors, whose sum is σ = 91089210. Its totient is φ = 91089208.

The previous prime is 91089197. The next prime is 91089221. The reversal of 91089209 is 90298019.

It is a balanced prime because it is at equal distance from previous prime (91089197) and next prime (91089221).

It can be written as a sum of positive squares in only one way, i.e., 46199209 + 44890000 = 6797^2 + 6700^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91089209 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (91089109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45544604 + 45544605.

It is an arithmetic number, because the mean of its divisors is an integer number (45544605).

Almost surely, 2^91089209 is an apocalyptic number.

It is an amenable number.

91089209 is a deficient number, since it is larger than the sum of its proper divisors (1).

91089209 is an equidigital number, since it uses as much as digits as its factorization.

91089209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 91089209 is about 9544.0666908818. The cubic root of 91089209 is about 449.9410770586.

The spelling of 91089209 in words is "ninety-one million, eighty-nine thousand, two hundred nine".