81443872 has 24 divisors (see below), whose sum is σ = 169775676. Its totient is φ = 38326272.

The previous prime is 81443867. The next prime is 81443909. The reversal of 81443872 is 27834418.

It can be written as a sum of positive squares in 2 ways, for example, as 79495056 + 1948816 = 8916^2 + 1396^2 .

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, 74313 + ... + 75400.

Almost surely, 2^81443872 is an apocalyptic number.

It is an amenable number.

81443872 is an abundant number, since it is smaller than the sum of its proper divisors (88331804).

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

81443872 is a wasteful number, since it uses less digits than its factorization.

81443872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149740 (or 149732 counting only the distinct ones).

The product of its digits is 43008, while the sum is 37.

The square root of 81443872 is about 9024.6258648212. The cubic root of 81443872 is about 433.4637703324.

The spelling of 81443872 in words is "eighty-one million, four hundred forty-three thousand, eight hundred seventy-two".