20668009 has 4 divisors (see below), whose sum is σ = 20686420. Its totient is φ = 20649600.

The previous prime is 20667973. The next prime is 20668027. The reversal of 20668009 is 90086602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90086602 = 2 ⋅45043301.

It can be written as a sum of positive squares in 2 ways, for example, as 2985984 + 17682025 = 1728^2 + 4205^2 .

It is a cyclic number.

It is not a de Polignac number, because 20668009 - 2¹¹ = 20665961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20668069) 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, 7404 + ... + 9805.

It is an arithmetic number, because the mean of its divisors is an integer number (5171605).

Almost surely, 2^20668009 is an apocalyptic number.

It is an amenable number.

20668009 is a deficient number, since it is larger than the sum of its proper divisors (18411).

20668009 is a wasteful number, since it uses less digits than its factorization.

20668009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18410.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 20668009 is about 4546.2082002478. The cubic root of 20668009 is about 274.4308183405.

The spelling of 20668009 in words is "twenty million, six hundred sixty-eight thousand, nine".