19899899 has 4 divisors (see below), whose sum is σ = 20765136. Its totient is φ = 19034664.

The previous prime is 19899889. The next prime is 19899947. The reversal of 19899899 is 99899891.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 19899899 - 2¹⁶ = 19834363 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19899839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 432584 + ... + 432629.

It is an arithmetic number, because the mean of its divisors is an integer number (5191284).

Almost surely, 2^19899899 is an apocalyptic number.

19899899 is a deficient number, since it is larger than the sum of its proper divisors (865237).

19899899 is an equidigital number, since it uses as much as digits as its factorization.

19899899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 865236.

The product of its digits is 3779136, while the sum is 62.

The square root of 19899899 is about 4460.9302841448. The cubic root of 19899899 is about 270.9881441598.

The spelling of 19899899 in words is "nineteen million, eight hundred ninety-nine thousand, eight hundred ninety-nine".