991031220323 has 2 divisors, whose sum is σ = 991031220324. Its totient is φ = 991031220322.

The previous prime is 991031220313. The next prime is 991031220337. The reversal of 991031220323 is 323022130199.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (323022130199) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 991031220323 - 2¹⁸ = 991030958179 is a prime.

It is not a weakly prime, because it can be changed into another prime (991031220313) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495515610161 + 495515610162.

It is an arithmetic number, because the mean of its divisors is an integer number (495515610162).

Almost surely, 2^991031220323 is an apocalyptic number.

991031220323 is a deficient number, since it is larger than the sum of its proper divisors (1).

991031220323 is an equidigital number, since it uses as much as digits as its factorization.

991031220323 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496, while the sum is 35.

The spelling of 991031220323 in words is "nine hundred ninety-one billion, thirty-one million, two hundred twenty thousand, three hundred twenty-three".