81388008 has 96 divisors (see below), whose sum is σ = 240294600. Its totient is φ = 24735744.

The previous prime is 81387991. The next prime is 81388009. The reversal of 81388008 is 80088318.

It can be written as a sum of positive squares in 4 ways, for example, as 63393444 + 17994564 = 7962^2 + 4242^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (81388009) 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, 82816 + ... + 83792.

Almost surely, 2^81388008 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 81388008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120147300).

81388008 is an abundant number, since it is smaller than the sum of its proper divisors (158906592).

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

81388008 is a wasteful number, since it uses less digits than its factorization.

81388008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1091 (or 1084 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 36.

The square root of 81388008 is about 9021.5302471366. The cubic root of 81388008 is about 433.3646404731.

The spelling of 81388008 in words is "eighty-one million, three hundred eighty-eight thousand, eight".