81728670 has 32 divisors (see below), whose sum is σ = 202914720. Its totient is φ = 21042560.

The previous prime is 81728659. The next prime is 81728693. The reversal of 81728670 is 7682718.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46101 + ... + 47840.

It is an arithmetic number, because the mean of its divisors is an integer number (6341085).

Almost surely, 2^81728670 is an apocalyptic number.

81728670 is an abundant number, since it is smaller than the sum of its proper divisors (121186050).

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

81728670 is a wasteful number, since it uses less digits than its factorization.

81728670 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93980.

The product of its (nonzero) digits is 37632, while the sum is 39.

The square root of 81728670 is about 9040.3910313658. The cubic root of 81728670 is about 433.9684369013.

The spelling of 81728670 in words is "eighty-one million, seven hundred twenty-eight thousand, six hundred seventy".