81689983 has 4 divisors (see below), whose sum is σ = 81717048. Its totient is φ = 81662920.

The previous prime is 81689977. The next prime is 81689989. The reversal of 81689983 is 38998618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 38998618 = 2 ⋅19499309.

It is an interprime number because it is at equal distance from previous prime (81689977) and next prime (81689989).

It is a cyclic number.

It is not a de Polignac number, because 81689983 - 2²¹ = 79592831 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 81689983.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81689989) 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, 8341 + ... + 15262.

It is an arithmetic number, because the mean of its divisors is an integer number (20429262).

Almost surely, 2^81689983 is an apocalyptic number.

81689983 is a deficient number, since it is larger than the sum of its proper divisors (27065).

81689983 is a wasteful number, since it uses less digits than its factorization.

81689983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27064.

The product of its digits is 746496, while the sum is 52.

The square root of 81689983 is about 9038.2511029513. The cubic root of 81689983 is about 433.8999518084.

The spelling of 81689983 in words is "eighty-one million, six hundred eighty-nine thousand, nine hundred eighty-three".