81567904 has 96 divisors (see below), whose sum is σ = 190403136. Its totient is φ = 33976320.

The previous prime is 81567883. The next prime is 81567929. The reversal of 81567904 is 40976518.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 257154 + ... + 257470.

It is an arithmetic number, because the mean of its divisors is an integer number (1983366).

Almost surely, 2^81567904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81567904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (95201568).

81567904 is an abundant number, since it is smaller than the sum of its proper divisors (108835232).

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

81567904 is a wasteful number, since it uses less digits than its factorization.

81567904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 398 (or 390 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 40.

The square root of 81567904 is about 9031.4951143208. The cubic root of 81567904 is about 433.6837013834.

The spelling of 81567904 in words is "eighty-one million, five hundred sixty-seven thousand, nine hundred four".