81728550 has 36 divisors (see below), whose sum is σ = 219578580. Its totient is φ = 21794160.

The previous prime is 81728531. The next prime is 81728561. The reversal of 81728550 is 5582718.

81728550 is a `hidden beast` number, since 81 + 7 + 28 + 550 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 17 ways as a sum of consecutive naturals, for example, 90360 + ... + 91259.

It is an arithmetic number, because the mean of its divisors is an integer number (6099405).

Almost surely, 2^81728550 is an apocalyptic number.

81728550 is an abundant number, since it is smaller than the sum of its proper divisors (137850030).

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

81728550 is a wasteful number, since it uses less digits than its factorization.

81728550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181637 (or 181629 counting only the distinct ones).

The product of its (nonzero) digits is 22400, while the sum is 36.

The square root of 81728550 is about 9040.3843944823. The cubic root of 81728550 is about 433.9682245065.

The spelling of 81728550 in words is "eighty-one million, seven hundred twenty-eight thousand, five hundred fifty".