81528225 has 24 divisors (see below), whose sum is σ = 136648992. Its totient is φ = 42883200.

The previous prime is 81528217. The next prime is 81528229. The reversal of 81528225 is 52282518.

It is not a de Polignac number, because 81528225 - 2³ = 81528217 is a prime.

It is a Curzon number.

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

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1971 + ... + 12920.

It is an arithmetic number, because the mean of its divisors is an integer number (5693708).

Almost surely, 2^81528225 is an apocalyptic number.

It is an amenable number.

81528225 is a deficient number, since it is larger than the sum of its proper divisors (55120767).

81528225 is a wasteful number, since it uses less digits than its factorization.

81528225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14977 (or 14972 counting only the distinct ones).

The product of its digits is 12800, while the sum is 33.

The square root of 81528225 is about 9029.2981454817. The cubic root of 81528225 is about 433.6133676458.

The spelling of 81528225 in words is "eighty-one million, five hundred twenty-eight thousand, two hundred twenty-five".