81857411 has 2 divisors, whose sum is σ = 81857412. Its totient is φ = 81857410.

The previous prime is 81857393. The next prime is 81857417. The reversal of 81857411 is 11475818.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81857411 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81857417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40928705 + 40928706.

It is an arithmetic number, because the mean of its divisors is an integer number (40928706).

Almost surely, 2^81857411 is an apocalyptic number.

81857411 is a deficient number, since it is larger than the sum of its proper divisors (1).

81857411 is an equidigital number, since it uses as much as digits as its factorization.

81857411 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8960, while the sum is 35.

The square root of 81857411 is about 9047.5085520822. The cubic root of 81857411 is about 434.1961832580.

The spelling of 81857411 in words is "eighty-one million, eight hundred fifty-seven thousand, four hundred eleven".