81385924 has 12 divisors (see below), whose sum is σ = 142941484. Its totient is φ = 40545504.

The previous prime is 81385921. The next prime is 81385933. The reversal of 81385924 is 42958318.

It can be written as a sum of positive squares in 2 ways, for example, as 32832900 + 48553024 = 5730^2 + 6968^2 .

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (81385921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35619 + ... + 37834.

Almost surely, 2^81385924 is an apocalyptic number.

It is an amenable number.

81385924 is a deficient number, since it is larger than the sum of its proper divisors (61555560).

81385924 is a wasteful number, since it uses less digits than its factorization.

81385924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73734 (or 73732 counting only the distinct ones).

The product of its digits is 69120, while the sum is 40.

The square root of 81385924 is about 9021.4147449278. The cubic root of 81385924 is about 433.3609415678.

The spelling of 81385924 in words is "eighty-one million, three hundred eighty-five thousand, nine hundred twenty-four".