81647728 has 40 divisors (see below), whose sum is σ = 164426976. Its totient is φ = 39244800.

The previous prime is 81647717. The next prime is 81647759. The reversal of 81647728 is 82774618.

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, 45700 + ... + 47452.

Almost surely, 2^81647728 is an apocalyptic number.

It is an amenable number.

81647728 is an abundant number, since it is smaller than the sum of its proper divisors (82779248).

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

81647728 is a wasteful number, since it uses less digits than its factorization.

81647728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1873 (or 1867 counting only the distinct ones).

The product of its digits is 150528, while the sum is 43.

The square root of 81647728 is about 9035.9132355285. The cubic root of 81647728 is about 433.8251258059.

The spelling of 81647728 in words is "eighty-one million, six hundred forty-seven thousand, seven hundred twenty-eight".