81536418 has 24 divisors (see below), whose sum is σ = 176939100. Its totient is φ = 27136224.

The previous prime is 81536383. The next prime is 81536423. The reversal of 81536418 is 81463518.

81536418 is a `hidden beast` number, since 8 + 1 + 5 + 3 + 641 + 8 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 57653649 + 23882769 = 7593^2 + 4887^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9568 + ... + 15956.

Almost surely, 2^81536418 is an apocalyptic number.

81536418 is an abundant number, since it is smaller than the sum of its proper divisors (95402682).

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

81536418 is a wasteful number, since it uses less digits than its factorization.

81536418 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7106 (or 7103 counting only the distinct ones).

The product of its digits is 23040, while the sum is 36.

The square root of 81536418 is about 9029.7518238321. The cubic root of 81536418 is about 433.6278921671.

Subtracting from 81536418 its reverse (81463518), we obtain a square (72900 = 270²).

The spelling of 81536418 in words is "eighty-one million, five hundred thirty-six thousand, four hundred eighteen".