81807899 has 2 divisors, whose sum is σ = 81807900. Its totient is φ = 81807898.

The previous prime is 81807883. The next prime is 81807911. The reversal of 81807899 is 99870818.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81807899 - 2⁴ = 81807883 is a prime.

It is not a weakly prime, because it can be changed into another prime (81807809) 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, 40903949 + 40903950.

It is an arithmetic number, because the mean of its divisors is an integer number (40903950).

Almost surely, 2^81807899 is an apocalyptic number.

81807899 is a deficient number, since it is larger than the sum of its proper divisors (1).

81807899 is an equidigital number, since it uses as much as digits as its factorization.

81807899 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 290304, while the sum is 50.

The square root of 81807899 is about 9044.7719153111. The cubic root of 81807899 is about 434.1086234512.

The spelling of 81807899 in words is "eighty-one million, eight hundred seven thousand, eight hundred ninety-nine".