19913 has 2 divisors, whose sum is σ = 19914. Its totient is φ = 19912.

The previous prime is 19891. The next prime is 19919. The reversal of 19913 is 31991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11449 + 8464 = 107^2 + 92^2 .

It is an emirp because it is prime and its reverse (31991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19913 - 2¹² = 15817 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (19919) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9956 + 9957.

It is an arithmetic number, because the mean of its divisors is an integer number (9957).

2¹⁹⁹¹³ is an apocalyptic number.

It is an amenable number.

19913 is a deficient number, since it is larger than the sum of its proper divisors (1).

19913 is an equidigital number, since it uses as much as digits as its factorization.

19913 is an evil number, because the sum of its binary digits is even.

The product of its digits is 243, while the sum is 23.

The square root of 19913 is about 141.1134295523. The cubic root of 19913 is about 27.1047599016.

It can be divided in two parts, 199 and 13, that added together give a palindrome (212).

The spelling of 19913 in words is "nineteen thousand, nine hundred thirteen".