91855609 has 2 divisors, whose sum is σ = 91855610. Its totient is φ = 91855608.

The previous prime is 91855579. The next prime is 91855613. The reversal of 91855609 is 90655819.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 89359209 + 2496400 = 9453^2 + 1580^2 .

It is an emirp because it is prime and its reverse (90655819) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91855609 is a prime.

It is not a weakly prime, because it can be changed into another prime (91855639) 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, 45927804 + 45927805.

It is an arithmetic number, because the mean of its divisors is an integer number (45927805).

Almost surely, 2^91855609 is an apocalyptic number.

It is an amenable number.

91855609 is a deficient number, since it is larger than the sum of its proper divisors (1).

91855609 is an equidigital number, since it uses as much as digits as its factorization.

91855609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 97200, while the sum is 43.

The square root of 91855609 is about 9584.1331898091. The cubic root of 91855609 is about 451.1994486590.

The spelling of 91855609 in words is "ninety-one million, eight hundred fifty-five thousand, six hundred nine".