81368500 has 48 divisors (see below), whose sum is σ = 179459280. Its totient is φ = 32227200.

The previous prime is 81368491. The next prime is 81368527. The reversal of 81368500 is 586318.

It can be written as a sum of positive squares in 8 ways, for example, as 6822544 + 74545956 = 2612^2 + 8634^2 .

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, 53754 + ... + 55246.

It is an arithmetic number, because the mean of its divisors is an integer number (3738735).

Almost surely, 2^81368500 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 81368500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (89729640).

81368500 is an abundant number, since it is smaller than the sum of its proper divisors (98090780).

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

81368500 is a wasteful number, since it uses less digits than its factorization.

81368500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1621 (or 1609 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 81368500 is about 9020.4489910425. The cubic root of 81368500 is about 433.3300131238.

The spelling of 81368500 in words is "eighty-one million, three hundred sixty-eight thousand, five hundred".