81776816 has 40 divisors (see below), whose sum is σ = 173686800. Its totient is φ = 36990720.

The previous prime is 81776797. The next prime is 81776869. The reversal of 81776816 is 61867718.

It is a Harshad number since it is a multiple of its sum of digits (44).

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, 39290 + ... + 41318.

It is an arithmetic number, because the mean of its divisors is an integer number (4342170).

Almost surely, 2^81776816 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 81776816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (86843400).

81776816 is an abundant number, since it is smaller than the sum of its proper divisors (91909984).

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

81776816 is a wasteful number, since it uses less digits than its factorization.

81776816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2277 (or 2271 counting only the distinct ones).

The product of its digits is 112896, while the sum is 44.

The square root of 81776816 is about 9043.0534666118. The cubic root of 81776816 is about 434.0536364724.

The spelling of 81776816 in words is "eighty-one million, seven hundred seventy-six thousand, eight hundred sixteen".