81800791 has 2 divisors, whose sum is σ = 81800792. Its totient is φ = 81800790.

The previous prime is 81800759. The next prime is 81800819. The reversal of 81800791 is 19700818.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81800791 - 2⁵ = 81800759 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81800711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40900395 + 40900396.

It is an arithmetic number, because the mean of its divisors is an integer number (40900396).

Almost surely, 2^81800791 is an apocalyptic number.

81800791 is a deficient number, since it is larger than the sum of its proper divisors (1).

81800791 is an equidigital number, since it uses as much as digits as its factorization.

81800791 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 34.

The square root of 81800791 is about 9044.3789725995. The cubic root of 81800791 is about 434.0960503644.

The spelling of 81800791 in words is "eighty-one million, eight hundred thousand, seven hundred ninety-one".