91389186661 has 2 divisors, whose sum is σ = 91389186662. Its totient is φ = 91389186660.

The previous prime is 91389186659. The next prime is 91389186739. The reversal of 91389186661 is 16668198319.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62252745025 + 29136441636 = 249505^2 + 170694^2 .

It is an emirp because it is prime and its reverse (16668198319) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91389186661 - 2¹ = 91389186659 is a prime.

Together with 91389186659, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 91389186596 and 91389186605.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91389186061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45694593330 + 45694593331.

It is an arithmetic number, because the mean of its divisors is an integer number (45694593331).

Almost surely, 2^91389186661 is an apocalyptic number.

It is an amenable number.

91389186661 is a deficient number, since it is larger than the sum of its proper divisors (1).

91389186661 is an equidigital number, since it uses as much as digits as its factorization.

91389186661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3359232, while the sum is 58.

The spelling of 91389186661 in words is "ninety-one billion, three hundred eighty-nine million, one hundred eighty-six thousand, six hundred sixty-one".