991010023 has 2 divisors, whose sum is σ = 991010024. Its totient is φ = 991010022.

The previous prime is 991010021. The next prime is 991010029. The reversal of 991010023 is 320010199.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 991010023 - 2¹ = 991010021 is a prime.

Together with 991010021, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 991010023.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991010021) 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, 495505011 + 495505012.

It is an arithmetic number, because the mean of its divisors is an integer number (495505012).

Almost surely, 2^991010023 is an apocalyptic number.

991010023 is a deficient number, since it is larger than the sum of its proper divisors (1).

991010023 is an equidigital number, since it uses as much as digits as its factorization.

991010023 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 486, while the sum is 25.

The square root of 991010023 is about 31480.3116725359. The cubic root of 991010023 is about 996.9943159144.

The spelling of 991010023 in words is "nine hundred ninety-one million, ten thousand, twenty-three".