19788109 has 4 divisors (see below), whose sum is σ = 21587040. Its totient is φ = 17989180.

The previous prime is 19788089. The next prime is 19788151. The reversal of 19788109 is 90188791.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 19788109 - 2⁵ = 19788077 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19788169) 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, 899449 + ... + 899470.

It is an arithmetic number, because the mean of its divisors is an integer number (5396760).

Almost surely, 2^19788109 is an apocalyptic number.

It is an amenable number.

19788109 is a deficient number, since it is larger than the sum of its proper divisors (1798931).

19788109 is a wasteful number, since it uses less digits than its factorization.

19788109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1798930.

The product of its (nonzero) digits is 36288, while the sum is 43.

The square root of 19788109 is about 4448.3827398280. The cubic root of 19788109 is about 270.4797551710.

The spelling of 19788109 in words is "nineteen million, seven hundred eighty-eight thousand, one hundred nine".