191812813 has 2 divisors, whose sum is σ = 191812814. Its totient is φ = 191812812.

The previous prime is 191812811. The next prime is 191812849. The reversal of 191812813 is 318218191.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 166229449 + 25583364 = 12893^2 + 5058^2 .

It is a cyclic number.

It is not a de Polignac number, because 191812813 - 2¹ = 191812811 is a prime.

Together with 191812811, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191812811) 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, 95906406 + 95906407.

It is an arithmetic number, because the mean of its divisors is an integer number (95906407).

Almost surely, 2^191812813 is an apocalyptic number.

It is an amenable number.

191812813 is a deficient number, since it is larger than the sum of its proper divisors (1).

191812813 is an equidigital number, since it uses as much as digits as its factorization.

191812813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456, while the sum is 34.

The square root of 191812813 is about 13849.6502843935. The cubic root of 191812813 is about 576.7122877395.

The spelling of 191812813 in words is "one hundred ninety-one million, eight hundred twelve thousand, eight hundred thirteen".