20937708857 has 4 divisors (see below), whose sum is σ = 22548301860. Its totient is φ = 19327115856.

The previous prime is 20937708761. The next prime is 20937708923. The reversal of 20937708857 is 75880773902.

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 6626611216 + 14311097641 = 81404^2 + 119629^2 .

It is a cyclic number.

It is not a de Polignac number, because 20937708857 - 2²⁰ = 20936660281 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20937708457) 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, 805296482 + ... + 805296507.

It is an arithmetic number, because the mean of its divisors is an integer number (5637075465).

Almost surely, 2^20937708857 is an apocalyptic number.

It is an amenable number.

20937708857 is a deficient number, since it is larger than the sum of its proper divisors (1610593003).

20937708857 is a wasteful number, since it uses less digits than its factorization.

20937708857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1610593002.

The product of its (nonzero) digits is 5927040, while the sum is 56.

The spelling of 20937708857 in words is "twenty billion, nine hundred thirty-seven million, seven hundred eight thousand, eight hundred fifty-seven".