81813888 has 160 divisors (see below), whose sum is σ = 262637760. Its totient is φ = 25132032.

The previous prime is 81813883. The next prime is 81813899. The reversal of 81813888 is 88831818.

It is a happy number.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81813881) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 134481 + ... + 135087.

It is an arithmetic number, because the mean of its divisors is an integer number (1641486).

Almost surely, 2^81813888 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 81813888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (131318880).

81813888 is an abundant number, since it is smaller than the sum of its proper divisors (180823872).

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

81813888 is a wasteful number, since it uses less digits than its factorization.

81813888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 646 (or 625 counting only the distinct ones).

The product of its digits is 98304, while the sum is 45.

The square root of 81813888 is about 9045.1029844883. The cubic root of 81813888 is about 434.1192166138.

It can be divided in two parts, 818 and 13888, that added together give a triangular number (14706 = T₁₇₁).

The spelling of 81813888 in words is "eighty-one million, eight hundred thirteen thousand, eight hundred eighty-eight".