20857713509 has 2 divisors, whose sum is σ = 20857713510. Its totient is φ = 20857713508.

The previous prime is 20857713493. The next prime is 20857713511. The reversal of 20857713509 is 90531775802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20191557409 + 666156100 = 142097^2 + 25810^2 .

It is a cyclic number.

It is not a de Polignac number, because 20857713509 - 2⁴ = 20857713493 is a prime.

Together with 20857713511, 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 (20857710509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10428856754 + 10428856755.

It is an arithmetic number, because the mean of its divisors is an integer number (10428856755).

Almost surely, 2^20857713509 is an apocalyptic number.

It is an amenable number.

20857713509 is a deficient number, since it is larger than the sum of its proper divisors (1).

20857713509 is an equidigital number, since it uses as much as digits as its factorization.

20857713509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 529200, while the sum is 47.

The spelling of 20857713509 in words is "twenty billion, eight hundred fifty-seven million, seven hundred thirteen thousand, five hundred nine".