21122838857 has 4 divisors (see below), whose sum is σ = 21125018820. Its totient is φ = 21120658896.

The previous prime is 21122838833. The next prime is 21122838871. The reversal of 21122838857 is 75883822112.

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 15702345481 + 5420493376 = 125309^2 + 73624^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122838857 - 2²⁰ = 21121790281 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21122838157) 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, 1075382 + ... + 1094847.

It is an arithmetic number, because the mean of its divisors is an integer number (5281254705).

Almost surely, 2^21122838857 is an apocalyptic number.

It is an amenable number.

21122838857 is a deficient number, since it is larger than the sum of its proper divisors (2179963).

21122838857 is an equidigital number, since it uses as much as digits as its factorization.

21122838857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2179962.

The product of its digits is 430080, while the sum is 47.

The spelling of 21122838857 in words is "twenty-one billion, one hundred twenty-two million, eight hundred thirty-eight thousand, eight hundred fifty-seven".