19949819 has 2 divisors, whose sum is σ = 19949820. Its totient is φ = 19949818.

The previous prime is 19949779. The next prime is 19949827. The reversal of 19949819 is 91894991.

It is a strong prime.

It is an emirp because it is prime and its reverse (91894991) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19949819 is a prime.

It is a super-2 number, since 2×19949819² = 795990556265522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (19949849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9974909 + 9974910.

It is an arithmetic number, because the mean of its divisors is an integer number (9974910).

Almost surely, 2^19949819 is an apocalyptic number.

19949819 is a deficient number, since it is larger than the sum of its proper divisors (1).

19949819 is an equidigital number, since it uses as much as digits as its factorization.

19949819 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 209952, while the sum is 50.

The square root of 19949819 is about 4466.5220250213. The cubic root of 19949819 is about 271.2145512086.

The spelling of 19949819 in words is "nineteen million, nine hundred forty-nine thousand, eight hundred nineteen".