19919899 has 2 divisors, whose sum is σ = 19919900. Its totient is φ = 19919898.

The previous prime is 19919857. The next prime is 19919941. The reversal of 19919899 is 99891991.

It is a balanced prime because it is at equal distance from previous prime (19919857) and next prime (19919941).

It is an emirp because it is prime and its reverse (99891991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19919899 - 2⁹ = 19919387 is a prime.

It is not a weakly prime, because it can be changed into another prime (19919819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9959949 + 9959950.

It is an arithmetic number, because the mean of its divisors is an integer number (9959950).

Almost surely, 2^19919899 is an apocalyptic number.

19919899 is a deficient number, since it is larger than the sum of its proper divisors (1).

19919899 is an equidigital number, since it uses as much as digits as its factorization.

19919899 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 472392, while the sum is 55.

The square root of 19919899 is about 4463.1714060744. The cubic root of 19919899 is about 271.0788975220.

The spelling of 19919899 in words is "nineteen million, nine hundred nineteen thousand, eight hundred ninety-nine".