81596021 has 16 divisors (see below), whose sum is σ = 89324928. Its totient is φ = 74088000.

The previous prime is 81596003. The next prime is 81596029. The reversal of 81596021 is 12069518.

It is a cyclic number.

It is not a de Polignac number, because 81596021 - 2²² = 77401717 is a prime.

It is a Smith number, since the sum of its digits (32) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81596029) 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, 386606 + ... + 386816.

It is an arithmetic number, because the mean of its divisors is an integer number (5582808).

Almost surely, 2^81596021 is an apocalyptic number.

It is an amenable number.

81596021 is a deficient number, since it is larger than the sum of its proper divisors (7728907).

81596021 is a wasteful number, since it uses less digits than its factorization.

81596021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 572.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 81596021 is about 9033.0515884722. The cubic root of 81596021 is about 433.7335268793.

The spelling of 81596021 in words is "eighty-one million, five hundred ninety-six thousand, twenty-one".