20685839789 has 2 divisors, whose sum is σ = 20685839790. Its totient is φ = 20685839788.

The previous prime is 20685839753. The next prime is 20685839791. The reversal of 20685839789 is 98793858602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12374782564 + 8311057225 = 111242^2 + 91165^2 .

It is a cyclic number.

It is not a de Polignac number, because 20685839789 - 2²⁸ = 20417404333 is a prime.

Together with 20685839791, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20685839689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10342919894 + 10342919895.

It is an arithmetic number, because the mean of its divisors is an integer number (10342919895).

Almost surely, 2^20685839789 is an apocalyptic number.

It is an amenable number.

20685839789 is a deficient number, since it is larger than the sum of its proper divisors (1).

20685839789 is an equidigital number, since it uses as much as digits as its factorization.

20685839789 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 52254720, while the sum is 65.

The spelling of 20685839789 in words is "twenty billion, six hundred eighty-five million, eight hundred thirty-nine thousand, seven hundred eighty-nine".