81731724 has 24 divisors (see below), whose sum is σ = 194307120. Its totient is φ = 26729664.

The previous prime is 81731701. The next prime is 81731743. The reversal of 81731724 is 42713718.

It is a happy 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, 63619 + ... + 64890.

It is an arithmetic number, because the mean of its divisors is an integer number (8096130).

Almost surely, 2^81731724 is an apocalyptic number.

It is an amenable number.

81731724 is an abundant number, since it is smaller than the sum of its proper divisors (112575396).

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

81731724 is a wasteful number, since it uses less digits than its factorization.

81731724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128569 (or 128567 counting only the distinct ones).

The product of its digits is 9408, while the sum is 33.

The square root of 81731724 is about 9040.5599384109. The cubic root of 81731724 is about 433.9738422794.

The spelling of 81731724 in words is "eighty-one million, seven hundred thirty-one thousand, seven hundred twenty-four".