81817904 has 40 divisors (see below), whose sum is σ = 181797888. Its totient is φ = 34943040.

The previous prime is 81817873. The next prime is 81817913. The reversal of 81817904 is 40971818.

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, 35969 + ... + 38175.

Almost surely, 2^81817904 is an apocalyptic number.

It is an amenable number.

81817904 is an abundant number, since it is smaller than the sum of its proper divisors (99979984).

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

81817904 is a wasteful number, since it uses less digits than its factorization.

81817904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2553 (or 2547 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 38.

The square root of 81817904 is about 9045.3249803421. The cubic root of 81817904 is about 434.1263197038.

The spelling of 81817904 in words is "eighty-one million, eight hundred seventeen thousand, nine hundred four".