19729 has 4 divisors (see below), whose sum is σ = 20020. Its totient is φ = 19440.

The previous prime is 19727. The next prime is 19739. The reversal of 19729 is 92791.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 5329 + 14400 = 73^2 + 120^2 .

It is a cyclic number.

It is not a de Polignac number, because 19729 - 2¹ = 19727 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19697 and 19706.

It is not an unprimeable number, because it can be changed into a prime (19727) 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, 19 + ... + 199.

It is an arithmetic number, because the mean of its divisors is an integer number (5005).

2¹⁹⁷²⁹ is an apocalyptic number.

It is an amenable number.

19729 is a deficient number, since it is larger than the sum of its proper divisors (291).

19729 is a wasteful number, since it uses less digits than its factorization.

19729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290.

The product of its digits is 1134, while the sum is 28.

The square root of 19729 is about 140.4599587071. The cubic root of 19729 is about 27.0210170150.

Subtracting from 19729 its sum of digits (28), we obtain a triangular number (19701 = T₁₉₈).

It can be divided in two parts, 1 and 9729, that added together give a triangular number (9730 = T₁₃₉).

The spelling of 19729 in words is "nineteen thousand, seven hundred twenty-nine".