20128609 has 4 divisors (see below), whose sum is σ = 20429104. Its totient is φ = 19828116.

The previous prime is 20128607. The next prime is 20128631. The reversal of 20128609 is 90682102.

It is a happy number.

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 a cyclic number.

It is not a de Polignac number, because 20128609 - 2¹ = 20128607 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20128607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 150147 + ... + 150280.

It is an arithmetic number, because the mean of its divisors is an integer number (5107276).

Almost surely, 2^20128609 is an apocalyptic number.

It is an amenable number.

20128609 is a deficient number, since it is larger than the sum of its proper divisors (300495).

20128609 is an equidigital number, since it uses as much as digits as its factorization.

20128609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300494.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 20128609 is about 4486.4918366135. The cubic root of 20128609 is about 272.0223498431.

The spelling of 20128609 in words is "twenty million, one hundred twenty-eight thousand, six hundred nine".