20609609 has 4 divisors (see below), whose sum is σ = 20662980. Its totient is φ = 20556240.

The previous prime is 20609581. The next prime is 20609639. The reversal of 20609609 is 90690602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90690602 = 2 ⋅45345301.

It can be written as a sum of positive squares in 2 ways, for example, as 14592400 + 6017209 = 3820^2 + 2453^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20609609 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20609639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26102 + ... + 26879.

It is an arithmetic number, because the mean of its divisors is an integer number (5165745).

Almost surely, 2^20609609 is an apocalyptic number.

It is an amenable number.

20609609 is a deficient number, since it is larger than the sum of its proper divisors (53371).

20609609 is an equidigital number, since it uses as much as digits as its factorization.

20609609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53370.

The product of its (nonzero) digits is 5832, while the sum is 32.

The square root of 20609609 is about 4539.7807215768. The cubic root of 20609609 is about 274.1720951655.

The spelling of 20609609 in words is "twenty million, six hundred nine thousand, six hundred nine".