81900288 has 216 divisors, whose sum is σ = 263553360. Its totient is φ = 25067520.

The previous prime is 81900257. The next prime is 81900389. The reversal of 81900288 is 88200918.

It is a tau number, because it is divible by the number of its divisors (216).

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

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1997548 + ... + 1997588.

Almost surely, 2^81900288 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 81900288, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (131776680).

81900288 is an abundant number, since it is smaller than the sum of its proper divisors (181653072).

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

81900288 is a wasteful number, since it uses less digits than its factorization.

81900288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100 (or 63 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 36.

The square root of 81900288 is about 9049.8777892301. The cubic root of 81900288 is about 434.2719808347.

The spelling of 81900288 in words is "eighty-one million, nine hundred thousand, two hundred eighty-eight".