20640821209 has 8 divisors (see below), whose sum is σ = 21728870240. Its totient is φ = 19552941216.

The previous prime is 20640821191. The next prime is 20640821213. The reversal of 20640821209 is 90212804602.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20640821209 - 2¹⁷ = 20640690137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20640821239) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 266182 + ... + 334864.

It is an arithmetic number, because the mean of its divisors is an integer number (2716108780).

Almost surely, 2^20640821209 is an apocalyptic number.

It is an amenable number.

20640821209 is a deficient number, since it is larger than the sum of its proper divisors (1088049031).

20640821209 is a wasteful number, since it uses less digits than its factorization.

20640821209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84519.

The product of its (nonzero) digits is 13824, while the sum is 34.

The spelling of 20640821209 in words is "twenty billion, six hundred forty million, eight hundred twenty-one thousand, two hundred nine".