91866557 has 2 divisors, whose sum is σ = 91866558. Its totient is φ = 91866556.

The previous prime is 91866499. The next prime is 91866563. The reversal of 91866557 is 75566819.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 83375161 + 8491396 = 9131^2 + 2914^2 .

It is a cyclic number.

It is not a de Polignac number, because 91866557 - 2²⁰ = 90817981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91866587) 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, 45933278 + 45933279.

It is an arithmetic number, because the mean of its divisors is an integer number (45933279).

Almost surely, 2^91866557 is an apocalyptic number.

It is an amenable number.

91866557 is a deficient number, since it is larger than the sum of its proper divisors (1).

91866557 is an equidigital number, since it uses as much as digits as its factorization.

91866557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 453600, while the sum is 47.

The square root of 91866557 is about 9584.7043251214. The cubic root of 91866557 is about 451.2173736588.

The spelling of 91866557 in words is "ninety-one million, eight hundred sixty-six thousand, five hundred fifty-seven".