81899 has 2 divisors, whose sum is σ = 81900. Its totient is φ = 81898.

The previous prime is 81883. The next prime is 81901. The reversal of 81899 is 99818.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81899 - 2⁴ = 81883 is a prime.

Together with 81901, 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 (81839) 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, 40949 + 40950.

It is an arithmetic number, because the mean of its divisors is an integer number (40950).

2⁸¹⁸⁹⁹ is an apocalyptic number.

81899 is a deficient number, since it is larger than the sum of its proper divisors (1).

81899 is an equidigital number, since it uses as much as digits as its factorization.

81899 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 35.

The square root of 81899 is about 286.1800132784. The cubic root of 81899 is about 43.4269704305.

The spelling of 81899 in words is "eighty-one thousand, eight hundred ninety-nine".