91801609 has 2 divisors, whose sum is σ = 91801610. Its totient is φ = 91801608.

The previous prime is 91801601. The next prime is 91801621. The reversal of 91801609 is 90610819.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 57836025 + 33965584 = 7605^2 + 5828^2 .

It is a cyclic number.

It is not a de Polignac number, because 91801609 - 2³ = 91801601 is a prime.

It is not a weakly prime, because it can be changed into another prime (91801601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45900804 + 45900805.

It is an arithmetic number, because the mean of its divisors is an integer number (45900805).

Almost surely, 2^91801609 is an apocalyptic number.

It is an amenable number.

91801609 is a deficient number, since it is larger than the sum of its proper divisors (1).

91801609 is an equidigital number, since it uses as much as digits as its factorization.

91801609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 34.

The square root of 91801609 is about 9581.3156194752. The cubic root of 91801609 is about 451.1110144067. Note that the first 3 decimals are identical.

The spelling of 91801609 in words is "ninety-one million, eight hundred one thousand, six hundred nine".