19709 has 2 divisors, whose sum is σ = 19710. Its totient is φ = 19708.

The previous prime is 19699. The next prime is 19717. The reversal of 19709 is 90791.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16900 + 2809 = 130^2 + 53^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19709 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 19709.

It is not a weakly prime, because it can be changed into another prime (19739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9854 + 9855.

It is an arithmetic number, because the mean of its divisors is an integer number (9855).

2¹⁹⁷⁰⁹ is an apocalyptic number.

It is an amenable number.

19709 is a deficient number, since it is larger than the sum of its proper divisors (1).

19709 is an equidigital number, since it uses as much as digits as its factorization.

19709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 567, while the sum is 26.

The square root of 19709 is about 140.3887459877. The cubic root of 19709 is about 27.0118832009.

Subtracting from 19709 its sum of digits (26), we obtain a 9-th power (19683 = 3⁹).

The spelling of 19709 in words is "nineteen thousand, seven hundred nine".