91661764477 has 2 divisors, whose sum is σ = 91661764478. Its totient is φ = 91661764476.

The previous prime is 91661764451. The next prime is 91661764487. The reversal of 91661764477 is 77446716619.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 91404033561 + 257730916 = 302331^2 + 16054^2 .

It is a cyclic number.

It is not a de Polignac number, because 91661764477 - 2¹⁹ = 91661240189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91661764417) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45830882238 + 45830882239.

It is an arithmetic number, because the mean of its divisors is an integer number (45830882239).

Almost surely, 2^91661764477 is an apocalyptic number.

It is an amenable number.

91661764477 is a deficient number, since it is larger than the sum of its proper divisors (1).

91661764477 is an equidigital number, since it uses as much as digits as its factorization.

91661764477 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10668672, while the sum is 58.

The spelling of 91661764477 in words is "ninety-one billion, six hundred sixty-one million, seven hundred sixty-four thousand, four hundred seventy-seven".