81199771 has 2 divisors, whose sum is σ = 81199772. Its totient is φ = 81199770.

The previous prime is 81199751. The next prime is 81199777. The reversal of 81199771 is 17799118.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81199771 - 2²¹ = 79102619 is a prime.

It is not a weakly prime, because it can be changed into another prime (81199777) 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, 40599885 + 40599886.

It is an arithmetic number, because the mean of its divisors is an integer number (40599886).

Almost surely, 2^81199771 is an apocalyptic number.

81199771 is a deficient number, since it is larger than the sum of its proper divisors (1).

81199771 is an equidigital number, since it uses as much as digits as its factorization.

81199771 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31752, while the sum is 43.

The square root of 81199771 is about 9011.0915543013. The cubic root of 81199771 is about 433.0302823255.

The spelling of 81199771 in words is "eighty-one million, one hundred ninety-nine thousand, seven hundred seventy-one".