81538904 has 16 divisors (see below), whose sum is σ = 153484200. Its totient is φ = 40609792.

The previous prime is 81538903. The next prime is 81538921. The reversal of 81538904 is 40983518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81538903) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17774 + ... + 21885.

Almost surely, 2^81538904 is an apocalyptic number.

It is an amenable number.

81538904 is a deficient number, since it is larger than the sum of its proper divisors (71945296).

81538904 is a wasteful number, since it uses less digits than its factorization.

81538904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39922 (or 39918 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 38.

The square root of 81538904 is about 9029.8894788364. The cubic root of 81538904 is about 433.6322991467.

The spelling of 81538904 in words is "eighty-one million, five hundred thirty-eight thousand, nine hundred four".