21022020121 has 2 divisors, whose sum is σ = 21022020122. Its totient is φ = 21022020120.

The previous prime is 21022020119. The next prime is 21022020139. The reversal of 21022020121 is 12102022012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16735044496 + 4286975625 = 129364^2 + 65475^2 .

It is a cyclic number.

It is not a de Polignac number, because 21022020121 - 2¹ = 21022020119 is a prime.

Together with 21022020119, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21022020101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10511010060 + 10511010061.

It is an arithmetic number, because the mean of its divisors is an integer number (10511010061).

Almost surely, 2^21022020121 is an apocalyptic number.

It is an amenable number.

21022020121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21022020121 is an equidigital number, since it uses as much as digits as its factorization.

21022020121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21022020121 its reverse (12102022012), we get a palindrome (33124042133).

The spelling of 21022020121 in words is "twenty-one billion, twenty-two million, twenty thousand, one hundred twenty-one".