81330724 has 12 divisors (see below), whose sum is σ = 142951900. Its totient is φ = 40487328.

The previous prime is 81330719. The next prime is 81330749. The reversal of 81330724 is 42703318.

It can be written as a sum of positive squares in 2 ways, for example, as 75377124 + 5953600 = 8682^2 + 2440^2 .

It is a super-2 number, since 2×81330724² = 13229373332728352, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81330692 and 81330701.

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, 43479 + ... + 45310.

Almost surely, 2^81330724 is an apocalyptic number.

It is an amenable number.

81330724 is a deficient number, since it is larger than the sum of its proper divisors (61621176).

81330724 is a wasteful number, since it uses less digits than its factorization.

81330724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89022 (or 89020 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 81330724 is about 9018.3548388828. The cubic root of 81330724 is about 433.2629437278.

The spelling of 81330724 in words is "eighty-one million, three hundred thirty thousand, seven hundred twenty-four".