81987828 has 48 divisors (see below), whose sum is σ = 207888576. Its totient is φ = 24998400.

The previous prime is 81987817. The next prime is 81987853. The reversal of 81987828 is 82878918.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15303 + ... + 19953.

It is an arithmetic number, because the mean of its divisors is an integer number (4331012).

Almost surely, 2^81987828 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 81987828, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (103944288).

81987828 is an abundant number, since it is smaller than the sum of its proper divisors (125900748).

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

81987828 is a wasteful number, since it uses less digits than its factorization.

81987828 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4784 (or 4782 counting only the distinct ones).

The product of its digits is 516096, while the sum is 51.

The square root of 81987828 is about 9054.7130269269. The cubic root of 81987828 is about 434.4266511600.

The spelling of 81987828 in words is "eighty-one million, nine hundred eighty-seven thousand, eight hundred twenty-eight".