81387128 has 16 divisors (see below), whose sum is σ = 152713080. Its totient is φ = 40663648.

The previous prime is 81387107. The next prime is 81387151. The reversal of 81387128 is 82178318.

It is a junction number, because it is equal to n+sod(n) for n = 81387091 and 81387100.

It is a congruent number.

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, 11450 + ... + 17142.

Almost surely, 2^81387128 is an apocalyptic number.

It is an amenable number.

81387128 is a deficient number, since it is larger than the sum of its proper divisors (71325952).

81387128 is a wasteful number, since it uses less digits than its factorization.

81387128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7486 (or 7482 counting only the distinct ones).

The product of its digits is 21504, while the sum is 38.

The square root of 81387128 is about 9021.4814747912. The cubic root of 81387128 is about 433.3630785630.

The spelling of 81387128 in words is "eighty-one million, three hundred eighty-seven thousand, one hundred twenty-eight".