91481809 has 2 divisors, whose sum is σ = 91481810. Its totient is φ = 91481808.

The previous prime is 91481773. The next prime is 91481839. The reversal of 91481809 is 90818419.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 91393600 + 88209 = 9560^2 + 297^2 .

It is a cyclic number.

It is not a de Polignac number, because 91481809 - 2¹⁵ = 91449041 is a prime.

It is not a weakly prime, because it can be changed into another prime (91481839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45740904 + 45740905.

It is an arithmetic number, because the mean of its divisors is an integer number (45740905).

Almost surely, 2^91481809 is an apocalyptic number.

It is an amenable number.

91481809 is a deficient number, since it is larger than the sum of its proper divisors (1).

91481809 is an equidigital number, since it uses as much as digits as its factorization.

91481809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 40.

The square root of 91481809 is about 9564.6123287878. The cubic root of 91481809 is about 450.5865749850.

The spelling of 91481809 in words is "ninety-one million, four hundred eighty-one thousand, eight hundred nine".