81604815 has 16 divisors (see below), whose sum is σ = 131510400. Its totient is φ = 43208352.

The previous prime is 81604813. The next prime is 81604819. The reversal of 81604815 is 51840618.

It is not a de Polignac number, because 81604815 - 2¹ = 81604813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81604813) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17485 + ... + 21654.

It is an arithmetic number, because the mean of its divisors is an integer number (8219400).

Almost surely, 2^81604815 is an apocalyptic number.

81604815 is a deficient number, since it is larger than the sum of its proper divisors (49905585).

81604815 is a wasteful number, since it uses less digits than its factorization.

81604815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39286.

The product of its (nonzero) digits is 7680, while the sum is 33.

The square root of 81604815 is about 9033.5383433071. The cubic root of 81604815 is about 433.7491081767.

The spelling of 81604815 in words is "eighty-one million, six hundred four thousand, eight hundred fifteen".