21220320613 has 2 divisors, whose sum is σ = 21220320614. Its totient is φ = 21220320612.

The previous prime is 21220320599. The next prime is 21220320619. The reversal of 21220320613 is 31602302212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11946052804 + 9274267809 = 109298^2 + 96303^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21220320613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21220320619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610160306 + 10610160307.

It is an arithmetic number, because the mean of its divisors is an integer number (10610160307).

Almost surely, 2^21220320613 is an apocalyptic number.

It is an amenable number.

21220320613 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220320613 is an equidigital number, since it uses as much as digits as its factorization.

21220320613 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 22.

Adding to 21220320613 its reverse (31602302212), we get a palindrome (52822622825).

The spelling of 21220320613 in words is "twenty-one billion, two hundred twenty million, three hundred twenty thousand, six hundred thirteen".