81528224 has 12 divisors (see below), whose sum is σ = 160508754. Its totient is φ = 40764096.

The previous prime is 81528217. The next prime is 81528229. The reversal of 81528224 is 42282518.

It can be written as a sum of positive squares in only one way, i.e., 72931600 + 8596624 = 8540^2 + 2932^2 .

It is a Harshad number since it is a multiple of its sum of digits (32), and also a Moran number because the ratio is a prime number: 2547757 = 81528224 / (8 + 1 + 5 + 2 + 8 + 2 + 2 + 4).

It is not an unprimeable number, because it can be changed into a prime (81528229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1273847 + ... + 1273910.

Almost surely, 2^81528224 is an apocalyptic number.

It is an amenable number.

81528224 is a deficient number, since it is larger than the sum of its proper divisors (78980530).

81528224 is a wasteful number, since it uses less digits than its factorization.

81528224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2547767 (or 2547759 counting only the distinct ones).

The product of its digits is 10240, while the sum is 32.

The square root of 81528224 is about 9029.2980901065. The cubic root of 81528224 is about 433.6133658729.

The spelling of 81528224 in words is "eighty-one million, five hundred twenty-eight thousand, two hundred twenty-four".