81578684 has 36 divisors (see below), whose sum is σ = 160787424. Its totient is φ = 36168000.

The previous prime is 81578671. The next prime is 81578689. The reversal of 81578684 is 48687518.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81578689) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17789 + ... + 21899.

Almost surely, 2^81578684 is an apocalyptic number.

It is an amenable number.

81578684 is a deficient number, since it is larger than the sum of its proper divisors (79208740).

81578684 is a wasteful number, since it uses less digits than its factorization.

81578684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4178 (or 4165 counting only the distinct ones).

The product of its digits is 430080, while the sum is 47.

The square root of 81578684 is about 9032.0918950152. The cubic root of 81578684 is about 433.7028057293.

The spelling of 81578684 in words is "eighty-one million, five hundred seventy-eight thousand, six hundred eighty-four".