191023813 has 2 divisors, whose sum is σ = 191023814. Its totient is φ = 191023812.

The previous prime is 191023793. The next prime is 191023831. The reversal of 191023813 is 318320191.

191023813 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

Together with next prime (191023831) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 179747649 + 11276164 = 13407^2 + 3358^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-191023813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191023843) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95511906 + 95511907.

It is an arithmetic number, because the mean of its divisors is an integer number (95511907).

Almost surely, 2^191023813 is an apocalyptic number.

It is an amenable number.

191023813 is a deficient number, since it is larger than the sum of its proper divisors (1).

191023813 is an equidigital number, since it uses as much as digits as its factorization.

191023813 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 191023813 is about 13821.1364583380. The cubic root of 191023813 is about 575.9204544297.

The spelling of 191023813 in words is "one hundred ninety-one million, twenty-three thousand, eight hundred thirteen".