81120784 has 10 divisors (see below), whose sum is σ = 157171550. Its totient is φ = 40560384.

The previous prime is 81120763. The next prime is 81120791. The reversal of 81120784 is 48702118.

It can be written as a sum of positive squares in only one way, i.e., 60217600 + 20903184 = 7760^2 + 4572^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2535009 + ... + 2535040.

It is an arithmetic number, because the mean of its divisors is an integer number (15717155).

Almost surely, 2^81120784 is an apocalyptic number.

It is an amenable number.

81120784 is a deficient number, since it is larger than the sum of its proper divisors (76050766).

81120784 is a wasteful number, since it uses less digits than its factorization.

81120784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5070057 (or 5070051 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 31.

The square root of 81120784 is about 9006.7077225810. The cubic root of 81120784 is about 432.8898268412.

The spelling of 81120784 in words is "eighty-one million, one hundred twenty thousand, seven hundred eighty-four".