81122791 has 2 divisors, whose sum is σ = 81122792. Its totient is φ = 81122790.

The previous prime is 81122779. The next prime is 81122819. The reversal of 81122791 is 19722118.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81122791 - 2⁷ = 81122663 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81122711) 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, 40561395 + 40561396.

It is an arithmetic number, because the mean of its divisors is an integer number (40561396).

Almost surely, 2^81122791 is an apocalyptic number.

81122791 is a deficient number, since it is larger than the sum of its proper divisors (1).

81122791 is an equidigital number, since it uses as much as digits as its factorization.

81122791 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 31.

The square root of 81122791 is about 9006.8191388525. The cubic root of 81122791 is about 432.8933968376.

The spelling of 81122791 in words is "eighty-one million, one hundred twenty-two thousand, seven hundred ninety-one".