81385136 has 40 divisors (see below), whose sum is σ = 186431520. Its totient is φ = 33675264.

The previous prime is 81385133. The next prime is 81385147. The reversal of 81385136 is 63158318.

It is a junction number, because it is equal to n+sod(n) for n = 81385096 and 81385105.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81385133) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9281 + ... + 15776.

It is an arithmetic number, because the mean of its divisors is an integer number (4660788).

Almost surely, 2^81385136 is an apocalyptic number.

It is an amenable number.

81385136 is an abundant number, since it is smaller than the sum of its proper divisors (105046384).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81385136 is a wasteful number, since it uses less digits than its factorization.

81385136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25101 (or 25095 counting only the distinct ones).

The product of its digits is 17280, while the sum is 35.

The square root of 81385136 is about 9021.3710709626. The cubic root of 81385136 is about 433.3595429249.

The spelling of 81385136 in words is "eighty-one million, three hundred eighty-five thousand, one hundred thirty-six".