21220313021 has 2 divisors, whose sum is σ = 21220313022. Its totient is φ = 21220313020.

The previous prime is 21220312991. The next prime is 21220313029. The reversal of 21220313021 is 12031302212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18425076121 + 2795236900 = 135739^2 + 52870^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21220313021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21220313029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610156510 + 10610156511.

It is an arithmetic number, because the mean of its divisors is an integer number (10610156511).

Almost surely, 2^21220313021 is an apocalyptic number.

It is an amenable number.

21220313021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220313021 is an equidigital number, since it uses as much as digits as its factorization.

21220313021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21220313021 its reverse (12031302212), we get a palindrome (33251615233).

The spelling of 21220313021 in words is "twenty-one billion, two hundred twenty million, three hundred thirteen thousand, twenty-one".