81645683 has 4 divisors (see below), whose sum is σ = 93309360. Its totient is φ = 69982008.

The previous prime is 81645677. The next prime is 81645761. The reversal of 81645683 is 38654618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 38654618 = 2 ⋅19327309.

It is a cyclic number.

It is not a de Polignac number, because 81645683 - 2⁴ = 81645667 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81645683.

It is not an unprimeable number, because it can be changed into a prime (81645583) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5831828 + ... + 5831841.

It is an arithmetic number, because the mean of its divisors is an integer number (23327340).

Almost surely, 2^81645683 is an apocalyptic number.

81645683 is a deficient number, since it is larger than the sum of its proper divisors (11663677).

81645683 is a wasteful number, since it uses less digits than its factorization.

81645683 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11663676.

The product of its digits is 138240, while the sum is 41.

The square root of 81645683 is about 9035.8000752562. The cubic root of 81645683 is about 433.8215038240.

It can be divided in two parts, 81645 and 683, that added together give a palindrome (82328).

The spelling of 81645683 in words is "eighty-one million, six hundred forty-five thousand, six hundred eighty-three".