81590688 has 72 divisors (see below), whose sum is σ = 240048900. Its totient is φ = 26256384.

The previous prime is 81590681. The next prime is 81590699. The reversal of 81590688 is 88609518.

It can be written as a sum of positive squares in 2 ways, for example, as 81216144 + 374544 = 9012^2 + 612^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is not an unprimeable number, because it can be changed into a prime (81590681) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3468 + ... + 13236.

Almost surely, 2^81590688 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 81590688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120024450).

81590688 is an abundant number, since it is smaller than the sum of its proper divisors (158458212).

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

81590688 is a wasteful number, since it uses less digits than its factorization.

81590688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9814 (or 9803 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 45.

The square root of 81590688 is about 9032.7563899399. The cubic root of 81590688 is about 433.7240772710.

The spelling of 81590688 in words is "eighty-one million, five hundred ninety thousand, six hundred eighty-eight".