81522816 has 64 divisors (see below), whose sum is σ = 221201280. Its totient is φ = 26590208.

The previous prime is 81522781. The next prime is 81522869. The reversal of 81522816 is 61822518.

It is a tau number, because it is divible by the number of its divisors (64).

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15790 + ... + 20306.

It is an arithmetic number, because the mean of its divisors is an integer number (3456270).

Almost surely, 2^81522816 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 81522816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (110600640).

81522816 is an abundant number, since it is smaller than the sum of its proper divisors (139678464).

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

81522816 is a wasteful number, since it uses less digits than its factorization.

81522816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4581 (or 4569 counting only the distinct ones).

The product of its digits is 7680, while the sum is 33.

The square root of 81522816 is about 9028.9986155719. The cubic root of 81522816 is about 433.6037780565.

The spelling of 81522816 in words is "eighty-one million, five hundred twenty-two thousand, eight hundred sixteen".