20430978209 has 4 divisors (see below), whose sum is σ = 20765912340. Its totient is φ = 20096044080.

The previous prime is 20430978167. The next prime is 20430978287. The reversal of 20430978209 is 90287903402.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 367105600 + 20063872609 = 19160^2 + 141647^2 .

It is a cyclic number.

It is not a de Polignac number, because 20430978209 - 2²⁰ = 20429929633 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20430978209.

It is not an unprimeable number, because it can be changed into a prime (20430978299) 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, 167466974 + ... + 167467095.

It is an arithmetic number, because the mean of its divisors is an integer number (5191478085).

Almost surely, 2^20430978209 is an apocalyptic number.

It is an amenable number.

20430978209 is a deficient number, since it is larger than the sum of its proper divisors (334934131).

20430978209 is an equidigital number, since it uses as much as digits as its factorization.

20430978209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334934130.

The product of its (nonzero) digits is 217728, while the sum is 44.

The spelling of 20430978209 in words is "twenty billion, four hundred thirty million, nine hundred seventy-eight thousand, two hundred nine".