81386985 has 32 divisors (see below), whose sum is σ = 132963840. Its totient is φ = 42501888.

The previous prime is 81386983. The next prime is 81386989. The reversal of 81386985 is 58968318.

It is not a de Polignac number, because 81386985 - 2¹ = 81386983 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81386983) 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 in 31 ways as a sum of consecutive naturals, for example, 204807 + ... + 205203.

It is an arithmetic number, because the mean of its divisors is an integer number (4155120).

Almost surely, 2^81386985 is an apocalyptic number.

It is an amenable number.

81386985 is a deficient number, since it is larger than the sum of its proper divisors (51576855).

81386985 is a wasteful number, since it uses less digits than its factorization.

81386985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 657.

The product of its digits is 414720, while the sum is 48.

The square root of 81386985 is about 9021.4735492601. The cubic root of 81386985 is about 433.3628247516.

The spelling of 81386985 in words is "eighty-one million, three hundred eighty-six thousand, nine hundred eighty-five".