81729983 has 4 divisors (see below), whose sum is σ = 82354008. Its totient is φ = 81105960.

The previous prime is 81729937. The next prime is 81730027. The reversal of 81729983 is 38992718.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 38992718 = 2 ⋅19496359.

It is a cyclic number.

It is not a de Polignac number, because 81729983 - 2²⁰ = 80681407 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81729913) 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, 311816 + ... + 312077.

It is an arithmetic number, because the mean of its divisors is an integer number (20588502).

Almost surely, 2^81729983 is an apocalyptic number.

81729983 is a deficient number, since it is larger than the sum of its proper divisors (624025).

81729983 is a wasteful number, since it uses less digits than its factorization.

81729983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 624024.

The product of its digits is 217728, while the sum is 47.

The square root of 81729983 is about 9040.4636496144. The cubic root of 81729983 is about 433.9707608410.

The spelling of 81729983 in words is "eighty-one million, seven hundred twenty-nine thousand, nine hundred eighty-three".