21056160821 has 2 divisors, whose sum is σ = 21056160822. Its totient is φ = 21056160820.

The previous prime is 21056160701. The next prime is 21056160871. The reversal of 21056160821 is 12806165012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19019443921 + 2036716900 = 137911^2 + 45130^2 .

It is a cyclic number.

It is not a de Polignac number, because 21056160821 - 2¹⁰ = 21056159797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21056160871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10528080410 + 10528080411.

It is an arithmetic number, because the mean of its divisors is an integer number (10528080411).

Almost surely, 2^21056160821 is an apocalyptic number.

It is an amenable number.

21056160821 is a deficient number, since it is larger than the sum of its proper divisors (1).

21056160821 is an equidigital number, since it uses as much as digits as its factorization.

21056160821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5760, while the sum is 32.

The spelling of 21056160821 in words is "twenty-one billion, fifty-six million, one hundred sixty thousand, eight hundred twenty-one".