81238188 has 24 divisors (see below), whose sum is σ = 193133808. Its totient is φ = 26568256.

The previous prime is 81238163. The next prime is 81238229. The reversal of 81238188 is 88183218.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 63231 + ... + 64502.

It is an arithmetic number, because the mean of its divisors is an integer number (8047242).

Almost surely, 2^81238188 is an apocalyptic number.

It is an amenable number.

81238188 is an abundant number, since it is smaller than the sum of its proper divisors (111895620).

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

81238188 is a wasteful number, since it uses less digits than its factorization.

81238188 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127793 (or 127791 counting only the distinct ones).

The product of its digits is 24576, while the sum is 39.

The square root of 81238188 is about 9013.2229529730. Note that the first 3 decimals coincide. The cubic root of 81238188 is about 433.0985629019.

The spelling of 81238188 in words is "eighty-one million, two hundred thirty-eight thousand, one hundred eighty-eight".