91211089 has 2 divisors, whose sum is σ = 91211090. Its totient is φ = 91211088.

The previous prime is 91211063. The next prime is 91211111. The reversal of 91211089 is 98011219.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 90098064 + 1113025 = 9492^2 + 1055^2 .

It is an emirp because it is prime and its reverse (98011219) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91211089 - 2⁷ = 91210961 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 91211089.

It is not a weakly prime, because it can be changed into another prime (91211009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45605544 + 45605545.

It is an arithmetic number, because the mean of its divisors is an integer number (45605545).

Almost surely, 2^91211089 is an apocalyptic number.

It is an amenable number.

91211089 is a deficient number, since it is larger than the sum of its proper divisors (1).

91211089 is an equidigital number, since it uses as much as digits as its factorization.

91211089 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 31.

The square root of 91211089 is about 9550.4496752771. The cubic root of 91211089 is about 450.1416656852.

It can be divided in two parts, 9 and 1211089, that multiplied together give a palindrome (10899801).

The spelling of 91211089 in words is "ninety-one million, two hundred eleven thousand, eighty-nine".