81005311 has 2 divisors, whose sum is σ = 81005312. Its totient is φ = 81005310.

The previous prime is 81005279. The next prime is 81005329. The reversal of 81005311 is 11350018.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81005311 - 2⁵ = 81005279 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81005711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40502655 + 40502656.

It is an arithmetic number, because the mean of its divisors is an integer number (40502656).

Almost surely, 2^81005311 is an apocalyptic number.

81005311 is a deficient number, since it is larger than the sum of its proper divisors (1).

81005311 is an equidigital number, since it uses as much as digits as its factorization.

81005311 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120, while the sum is 19.

The square root of 81005311 is about 9000.2950507192. The cubic root of 81005311 is about 432.6843274133.

Adding to 81005311 its reverse (11350018), we get a palindrome (92355329).

The spelling of 81005311 in words is "eighty-one million, five thousand, three hundred eleven".