21056160857 has 4 divisors (see below), whose sum is σ = 21056871696. Its totient is φ = 21055450020.

The previous prime is 21056160821. The next prime is 21056160871. The reversal of 21056160857 is 75806165012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21056160857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21056160887) 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, 308963 + ... + 370904.

It is an arithmetic number, because the mean of its divisors is an integer number (5264217924).

Almost surely, 2^21056160857 is an apocalyptic number.

It is an amenable number.

21056160857 is a deficient number, since it is larger than the sum of its proper divisors (710839).

21056160857 is an equidigital number, since it uses as much as digits as its factorization.

21056160857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 710838.

The product of its (nonzero) digits is 100800, while the sum is 41.

The spelling of 21056160857 in words is "twenty-one billion, fifty-six million, one hundred sixty thousand, eight hundred fifty-seven".