91009889 has 2 divisors, whose sum is σ = 91009890. Its totient is φ = 91009888.

The previous prime is 91009837. The next prime is 91009913. The reversal of 91009889 is 98890019.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 55249489 + 35760400 = 7433^2 + 5980^2 .

It is a cyclic number.

It is not a de Polignac number, because 91009889 - 2¹⁶ = 90944353 is a prime.

It is not a weakly prime, because it can be changed into another prime (91009189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45504944 + 45504945.

It is an arithmetic number, because the mean of its divisors is an integer number (45504945).

Almost surely, 2^91009889 is an apocalyptic number.

It is an amenable number.

91009889 is a deficient number, since it is larger than the sum of its proper divisors (1).

91009889 is an equidigital number, since it uses as much as digits as its factorization.

91009889 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46656, while the sum is 44.

The square root of 91009889 is about 9539.9103245261. The cubic root of 91009889 is about 449.8104370300.

The spelling of 91009889 in words is "ninety-one million, nine thousand, eight hundred eighty-nine".