19919 has 2 divisors, whose sum is σ = 19920. Its totient is φ = 19918.

The previous prime is 19913. The next prime is 19927. The reversal of 19919 is 91991.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19919 - 2¹² = 15823 is a prime.

It is a super-2 number, since 2×19919² = 793533122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 19891 and 19900.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9959 + 9960.

It is an arithmetic number, because the mean of its divisors is an integer number (9960).

2¹⁹⁹¹⁹ is an apocalyptic number.

19919 is a deficient number, since it is larger than the sum of its proper divisors (1).

19919 is an equidigital number, since it uses as much as digits as its factorization.

19919 is an evil number, because the sum of its binary digits is even.

The product of its digits is 729, while the sum is 29.

The square root of 19919 is about 141.1346874443. The cubic root of 19919 is about 27.1074819463.

The spelling of 19919 in words is "nineteen thousand, nine hundred nineteen".