81369385 has 4 divisors (see below), whose sum is σ = 97643268. Its totient is φ = 65095504.

The previous prime is 81369371. The next prime is 81369391. The reversal of 81369385 is 58396318.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8369449 + 72999936 = 2893^2 + 8544^2 .

It is a cyclic number.

It is not a de Polignac number, because 81369385 - 2¹³ = 81361193 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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, 8136934 + ... + 8136943.

It is an arithmetic number, because the mean of its divisors is an integer number (24410817).

Almost surely, 2^81369385 is an apocalyptic number.

It is an amenable number.

81369385 is a deficient number, since it is larger than the sum of its proper divisors (16273883).

81369385 is a wasteful number, since it uses less digits than its factorization.

81369385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16273882.

The product of its digits is 155520, while the sum is 43.

The square root of 81369385 is about 9020.4980461170. The cubic root of 81369385 is about 433.3315841481.

The spelling of 81369385 in words is "eighty-one million, three hundred sixty-nine thousand, three hundred eighty-five".