81930724 has 24 divisors (see below), whose sum is σ = 145180728. Its totient is φ = 40454400.

The previous prime is 81930721. The next prime is 81930727. The reversal of 81930724 is 42703918.

It is an interprime number because it is at equal distance from previous prime (81930721) and next prime (81930727).

It can be written as a sum of positive squares in 4 ways, for example, as 67732900 + 14197824 = 8230^2 + 3768^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81930724.

It is not an unprimeable number, because it can be changed into a prime (81930721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 136024 + ... + 136624.

It is an arithmetic number, because the mean of its divisors is an integer number (6049197).

Almost surely, 2^81930724 is an apocalyptic number.

It is an amenable number.

81930724 is a deficient number, since it is larger than the sum of its proper divisors (63250004).

81930724 is a wasteful number, since it uses less digits than its factorization.

81930724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 975 (or 973 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 81930724 is about 9051.5592027009. The cubic root of 81930724 is about 434.3257692700.

The spelling of 81930724 in words is "eighty-one million, nine hundred thirty thousand, seven hundred twenty-four".