81986365 has 4 divisors (see below), whose sum is σ = 98383644. Its totient is φ = 65589088.

The previous prime is 81986357. The next prime is 81986369. The reversal of 81986365 is 56368918.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56368918 = 2 ⋅28184459.

It can be written as a sum of positive squares in 2 ways, for example, as 30448324 + 51538041 = 5518^2 + 7179^2 .

It is a cyclic number.

It is not a de Polignac number, because 81986365 - 2³ = 81986357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81986369) 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 in 3 ways as a sum of consecutive naturals, for example, 8198632 + ... + 8198641.

It is an arithmetic number, because the mean of its divisors is an integer number (24595911).

Almost surely, 2^81986365 is an apocalyptic number.

It is an amenable number.

81986365 is a deficient number, since it is larger than the sum of its proper divisors (16397279).

81986365 is a wasteful number, since it uses less digits than its factorization.

81986365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16397278.

The product of its digits is 311040, while the sum is 46.

The square root of 81986365 is about 9054.6322399090. The cubic root of 81986365 is about 434.4240671587.

The spelling of 81986365 in words is "eighty-one million, nine hundred eighty-six thousand, three hundred sixty-five".