20321321621 has 2 divisors, whose sum is σ = 20321321622. Its totient is φ = 20321321620.

The previous prime is 20321321611. The next prime is 20321321719. The reversal of 20321321621 is 12612312302.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20075772721 + 245548900 = 141689^2 + 15670^2 .

It is a cyclic number.

It is not a de Polignac number, because 20321321621 - 2³⁴ = 3141452437 is a prime.

It is a super-2 number, since 2×20321321621² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20321321611) 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, 10160660810 + 10160660811.

It is an arithmetic number, because the mean of its divisors is an integer number (10160660811).

Almost surely, 2^20321321621 is an apocalyptic number.

It is an amenable number.

20321321621 is a deficient number, since it is larger than the sum of its proper divisors (1).

20321321621 is an equidigital number, since it uses as much as digits as its factorization.

20321321621 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 23.

Adding to 20321321621 its reverse (12612312302), we get a palindrome (32933633923).

The spelling of 20321321621 in words is "twenty billion, three hundred twenty-one million, three hundred twenty-one thousand, six hundred twenty-one".