81604520 has 16 divisors (see below), whose sum is σ = 183610260. Its totient is φ = 32641792.

The previous prime is 81604447. The next prime is 81604543. The reversal of 81604520 is 2540618.

It can be written as a sum of positive squares in 2 ways, for example, as 81036004 + 568516 = 9002^2 + 754^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81604520.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1020017 + ... + 1020096.

Almost surely, 2^81604520 is an apocalyptic number.

It is an amenable number.

81604520 is an abundant number, since it is smaller than the sum of its proper divisors (102005740).

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

81604520 is a wasteful number, since it uses less digits than its factorization.

81604520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2040124 (or 2040120 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 81604520 is about 9033.5220152496. The cubic root of 81604520 is about 433.7485855109.

The spelling of 81604520 in words is "eighty-one million, six hundred four thousand, five hundred twenty".