91998307409 has 2 divisors, whose sum is σ = 91998307410. Its totient is φ = 91998307408.

The previous prime is 91998307399. The next prime is 91998307411. The reversal of 91998307409 is 90470389919.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69984057025 + 22014250384 = 264545^2 + 148372^2 .

It is a cyclic number.

It is not a de Polignac number, because 91998307409 - 2¹⁶ = 91998241873 is a prime.

It is a super-2 number, since 2×91998307409² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain prime.

Together with 91998307411, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (91998306409) 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, 45999153704 + 45999153705.

It is an arithmetic number, because the mean of its divisors is an integer number (45999153705).

Almost surely, 2^91998307409 is an apocalyptic number.

It is an amenable number.

91998307409 is a deficient number, since it is larger than the sum of its proper divisors (1).

91998307409 is an equidigital number, since it uses as much as digits as its factorization.

91998307409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4408992, while the sum is 59.

The spelling of 91998307409 in words is "ninety-one billion, nine hundred ninety-eight million, three hundred seven thousand, four hundred nine".