20597688857 has 4 divisors (see below), whose sum is σ = 21307954020. Its totient is φ = 19887423696.

The previous prime is 20597688851. The next prime is 20597688883. The reversal of 20597688857 is 75888679502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75888679502 = 2 ⋅37944339751.

It can be written as a sum of positive squares in 2 ways, for example, as 9092766736 + 11504922121 = 95356^2 + 107261^2 .

It is a cyclic number.

It is not a de Polignac number, because 20597688857 - 2²⁸ = 20329253401 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20597688793 and 20597688802.

It is not an unprimeable number, because it can be changed into a prime (20597688851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 355132538 + ... + 355132595.

It is an arithmetic number, because the mean of its divisors is an integer number (5326988505).

Almost surely, 2^20597688857 is an apocalyptic number.

It is an amenable number.

20597688857 is a deficient number, since it is larger than the sum of its proper divisors (710265163).

20597688857 is an equidigital number, since it uses as much as digits as its factorization.

20597688857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 710265162.

The product of its (nonzero) digits is 67737600, while the sum is 65.

The spelling of 20597688857 in words is "twenty billion, five hundred ninety-seven million, six hundred eighty-eight thousand, eight hundred fifty-seven".