81728015 has 8 divisors (see below), whose sum is σ = 98197728. Its totient is φ = 65299680.

The previous prime is 81727981. The next prime is 81728021. The reversal of 81728015 is 51082718.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81728015 - 2¹⁰ = 81726991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5816 + ... + 14045.

It is an arithmetic number, because the mean of its divisors is an integer number (12274716).

Almost surely, 2^81728015 is an apocalyptic number.

81728015 is a deficient number, since it is larger than the sum of its proper divisors (16469713).

81728015 is a wasteful number, since it uses less digits than its factorization.

81728015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20689.

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 81728015 is about 9040.3548049841. The cubic root of 81728015 is about 433.9672775771.

The spelling of 81728015 in words is "eighty-one million, seven hundred twenty-eight thousand, fifteen".