81815532 has 24 divisors (see below), whose sum is σ = 194966016. Its totient is φ = 26691408.

The previous prime is 81815527. The next prime is 81815533. The reversal of 81815532 is 23551818.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 81815493 and 81815502.

It is not an unprimeable number, because it can be changed into a prime (81815533) 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, 71968 + ... + 73095.

It is an arithmetic number, because the mean of its divisors is an integer number (8123584).

Almost surely, 2^81815532 is an apocalyptic number.

It is an amenable number.

81815532 is an abundant number, since it is smaller than the sum of its proper divisors (113150484).

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

81815532 is a wasteful number, since it uses less digits than its factorization.

81815532 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145117 (or 145115 counting only the distinct ones).

The product of its digits is 9600, while the sum is 33.

The square root of 81815532 is about 9045.1938619357. The cubic root of 81815532 is about 434.1221243809.

The spelling of 81815532 in words is "eighty-one million, eight hundred fifteen thousand, five hundred thirty-two".