81186899 has 2 divisors, whose sum is σ = 81186900. Its totient is φ = 81186898.

The previous prime is 81186893. The next prime is 81186901. The reversal of 81186899 is 99868118.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81186899 - 2⁸ = 81186643 is a prime.

Together with 81186901, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81186893) 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, 40593449 + 40593450.

It is an arithmetic number, because the mean of its divisors is an integer number (40593450).

Almost surely, 2^81186899 is an apocalyptic number.

81186899 is a deficient number, since it is larger than the sum of its proper divisors (1).

81186899 is an equidigital number, since it uses as much as digits as its factorization.

81186899 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 248832, while the sum is 50.

The square root of 81186899 is about 9010.3772950970. The cubic root of 81186899 is about 433.0073994188.

The spelling of 81186899 in words is "eighty-one million, one hundred eighty-six thousand, eight hundred ninety-nine".