81386999 has 2 divisors, whose sum is σ = 81387000. Its totient is φ = 81386998.

The previous prime is 81386989. The next prime is 81387049. The reversal of 81386999 is 99968318.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81386999 - 2⁴ = 81386983 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81386999.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81386989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40693499 + 40693500.

It is an arithmetic number, because the mean of its divisors is an integer number (40693500).

Almost surely, 2^81386999 is an apocalyptic number.

81386999 is a deficient number, since it is larger than the sum of its proper divisors (1).

81386999 is an equidigital number, since it uses as much as digits as its factorization.

81386999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 839808, while the sum is 53.

The square root of 81386999 is about 9021.4743251865. The cubic root of 81386999 is about 433.3628496003.

The spelling of 81386999 in words is "eighty-one million, three hundred eighty-six thousand, nine hundred ninety-nine".