81943616 has 28 divisors (see below), whose sum is σ = 163080192. Its totient is φ = 40852608.

The previous prime is 81943601. The next prime is 81943651. The reversal of 81943616 is 61634918.

It is a self number, because there is not a number n which added to its sum of digits gives 81943616.

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, 22841 + ... + 26183.

Almost surely, 2^81943616 is an apocalyptic number.

It is an amenable number.

81943616 is a deficient number, since it is larger than the sum of its proper divisors (81136576).

81943616 is a wasteful number, since it uses less digits than its factorization.

81943616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3738 (or 3728 counting only the distinct ones).

The product of its digits is 31104, while the sum is 38.

The square root of 81943616 is about 9052.2713171889. The cubic root of 81943616 is about 434.3485488163.

The spelling of 81943616 in words is "eighty-one million, nine hundred forty-three thousand, six hundred sixteen".