81528773 has 4 divisors (see below), whose sum is σ = 84340140. Its totient is φ = 78717408.

The previous prime is 81528761. The next prime is 81528779. The reversal of 81528773 is 37782518.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 45792289 + 35736484 = 6767^2 + 5978^2 .

It is a cyclic number.

It is not a de Polignac number, because 81528773 - 2²² = 77334469 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81528773.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81528779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1405640 + ... + 1405697.

It is an arithmetic number, because the mean of its divisors is an integer number (21085035).

Almost surely, 2^81528773 is an apocalyptic number.

It is an amenable number.

81528773 is a deficient number, since it is larger than the sum of its proper divisors (2811367).

81528773 is a wasteful number, since it uses less digits than its factorization.

81528773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2811366.

The product of its digits is 94080, while the sum is 41.

The square root of 81528773 is about 9029.3284910895. The cubic root of 81528773 is about 433.6143391686.

The spelling of 81528773 in words is "eighty-one million, five hundred twenty-eight thousand, seven hundred seventy-three".