91818193909 has 16 divisors (see below), whose sum is σ = 101139019632. Its totient is φ = 82832375808.

The previous prime is 91818193891. The next prime is 91818193921. The reversal of 91818193909 is 90939181819.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 13513365009 + 78304828900 = 116247^2 + 279830^2 .

It is not a de Polignac number, because 91818193909 - 2⁵ = 91818193877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91818193109) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 82194 + ... + 436339.

It is an arithmetic number, because the mean of its divisors is an integer number (6321188727).

Almost surely, 2^91818193909 is an apocalyptic number.

It is an amenable number.

91818193909 is a deficient number, since it is larger than the sum of its proper divisors (9320825723).

91818193909 is a wasteful number, since it uses less digits than its factorization.

91818193909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 518856.

The product of its (nonzero) digits is 1259712, while the sum is 58.

The spelling of 91818193909 in words is "ninety-one billion, eight hundred eighteen million, one hundred ninety-three thousand, nine hundred nine".