81508699 has 2 divisors, whose sum is σ = 81508700. Its totient is φ = 81508698.

The previous prime is 81508633. The next prime is 81508709. The reversal of 81508699 is 99680518.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81508699 - 2¹⁹ = 80984411 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81508099) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40754349 + 40754350.

It is an arithmetic number, because the mean of its divisors is an integer number (40754350).

Almost surely, 2^81508699 is an apocalyptic number.

81508699 is a deficient number, since it is larger than the sum of its proper divisors (1).

81508699 is an equidigital number, since it uses as much as digits as its factorization.

81508699 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 155520, while the sum is 46.

The square root of 81508699 is about 9028.2168228283. The cubic root of 81508699 is about 433.5787480989.

The spelling of 81508699 in words is "eighty-one million, five hundred eight thousand, six hundred ninety-nine".