81536040 has 96 divisors (see below), whose sum is σ = 266240520. Its totient is φ = 21640704.

The previous prime is 81536027. The next prime is 81536047. The reversal of 81536040 is 4063518.

81536040 is a `hidden beast` number, since 8 + 1 + 53 + 604 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 65901924 + 15634116 = 8118^2 + 3954^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81535995 and 81536013.

It is not an unprimeable number, because it can be changed into a prime (81536047) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 105094 + ... + 105866.

Almost surely, 2^81536040 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81536040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (133120260).

81536040 is an abundant number, since it is smaller than the sum of its proper divisors (184704480).

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

81536040 is a wasteful number, since it uses less digits than its factorization.

81536040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1083 (or 1076 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 81536040 is about 9029.7308930001. The cubic root of 81536040 is about 433.6272220715.

Adding to 81536040 its reverse (4063518), we get a palindrome (85599558).

The spelling of 81536040 in words is "eighty-one million, five hundred thirty-six thousand, forty".