20190109 has 4 divisors (see below), whose sum is σ = 20445760. Its totient is φ = 19934460.

The previous prime is 20190097. The next prime is 20190161. The reversal of 20190109 is 90109102.

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, and also an emirpimes, since its reverse is a distinct semiprime: 90109102 = 2 ⋅45054551.

It is a cyclic number.

It is not a de Polignac number, because 20190109 - 2²¹ = 18092957 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20190109.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20191109) 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, 127707 + ... + 127864.

It is an arithmetic number, because the mean of its divisors is an integer number (5111440).

Almost surely, 2^20190109 is an apocalyptic number.

It is an amenable number.

20190109 is a deficient number, since it is larger than the sum of its proper divisors (255651).

20190109 is an equidigital number, since it uses as much as digits as its factorization.

20190109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255650.

The product of its (nonzero) digits is 162, while the sum is 22.

The square root of 20190109 is about 4493.3405168093. The cubic root of 20190109 is about 272.2991095757.

The spelling of 20190109 in words is "twenty million, one hundred ninety thousand, one hundred nine".