19999109 has 4 divisors (see below), whose sum is σ = 21537516. Its totient is φ = 18460704.

The previous prime is 19999069. The next prime is 19999117. The reversal of 19999109 is 90199991.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6235009 + 13764100 = 2497^2 + 3710^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19999109 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19999159) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 769184 + ... + 769209.

It is an arithmetic number, because the mean of its divisors is an integer number (5384379).

Almost surely, 2^19999109 is an apocalyptic number.

It is an amenable number.

19999109 is a deficient number, since it is larger than the sum of its proper divisors (1538407).

19999109 is a wasteful number, since it uses less digits than its factorization.

19999109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1538406.

The product of its (nonzero) digits is 59049, while the sum is 47.

The square root of 19999109 is about 4472.0363370617. The cubic root of 19999109 is about 271.4377306895.

The spelling of 19999109 in words is "nineteen million, nine hundred ninety-nine thousand, one hundred nine".