81819181819091 has 2 divisors, whose sum is σ = 81819181819092. Its totient is φ = 81819181819090.

The previous prime is 81819181819079. The next prime is 81819181819121. The reversal of 81819181819091 is 19091818191818.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81819181819091 - 2¹⁰ = 81819181818067 is a prime.

It is not a weakly prime, because it can be changed into another prime (81819181819891) 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, 40909590909545 + 40909590909546.

It is an arithmetic number, because the mean of its divisors is an integer number (40909590909546).

Almost surely, 2^{81819181819091} is an apocalyptic number.

81819181819091 is a deficient number, since it is larger than the sum of its proper divisors (1).

81819181819091 is an equidigital number, since it uses as much as digits as its factorization.

81819181819091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2985984, while the sum is 65.

The spelling of 81819181819091 in words is "eighty-one trillion, eight hundred nineteen billion, one hundred eighty-one million, eight hundred nineteen thousand, ninety-one".