81408816 has 60 divisors (see below), whose sum is σ = 229893768. Its totient is φ = 26890752.

The previous prime is 81408809. The next prime is 81408851. The reversal of 81408816 is 61880418.

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 11 ways as a sum of consecutive naturals, for example, 13771 + ... + 18773.

Almost surely, 2^81408816 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 81408816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114946884).

81408816 is an abundant number, since it is smaller than the sum of its proper divisors (148484952).

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

81408816 is a wasteful number, since it uses less digits than its factorization.

81408816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5130 (or 5121 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 36.

The square root of 81408816 is about 9022.6834145946. The cubic root of 81408816 is about 433.4015692676.

The spelling of 81408816 in words is "eighty-one million, four hundred eight thousand, eight hundred sixteen".