81739928 has 16 divisors (see below), whose sum is σ = 153506880. Its totient is φ = 40804768.

The previous prime is 81739897. The next prime is 81739943. The reversal of 81739928 is 82993718.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2600 + ... + 13047.

It is an arithmetic number, because the mean of its divisors is an integer number (9594180).

Almost surely, 2^81739928 is an apocalyptic number.

It is an amenable number.

81739928 is a deficient number, since it is larger than the sum of its proper divisors (71766952).

81739928 is a wasteful number, since it uses less digits than its factorization.

81739928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16306 (or 16302 counting only the distinct ones).

The product of its digits is 217728, while the sum is 47.

The square root of 81739928 is about 9041.0136599830. The cubic root of 81739928 is about 433.9883621505.

The spelling of 81739928 in words is "eighty-one million, seven hundred thirty-nine thousand, nine hundred twenty-eight".