81332784 has 120 divisors (see below), whose sum is σ = 255921120. Its totient is φ = 23924736.

The previous prime is 81332759. The next prime is 81332813. The reversal of 81332784 is 48723318.

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 23 ways as a sum of consecutive naturals, for example, 42112 + ... + 44000.

It is an arithmetic number, because the mean of its divisors is an integer number (2132676).

Almost surely, 2^81332784 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 81332784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (127960560).

81332784 is an abundant number, since it is smaller than the sum of its proper divisors (174588336).

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

81332784 is a wasteful number, since it uses less digits than its factorization.

81332784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1939 (or 1930 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 81332784 is about 9018.4690496780. The cubic root of 81332784 is about 433.2666016899.

The spelling of 81332784 in words is "eighty-one million, three hundred thirty-two thousand, seven hundred eighty-four".