21020021202121 has 2 divisors, whose sum is σ = 21020021202122. Its totient is φ = 21020021202120.

The previous prime is 21020021202109. The next prime is 21020021202133. The reversal of 21020021202121 is 12120212002012.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (21020021202109) and next prime (21020021202133).

It can be written as a sum of positive squares in only one way, i.e., 19357043312896 + 1662977889225 = 4399664^2 + 1289565^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020021202121 - 2²⁵ = 21019987647689 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21020021202095 and 21020021202104.

It is not a weakly prime, because it can be changed into another prime (21020021202151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510010601060 + 10510010601061.

It is an arithmetic number, because the mean of its divisors is an integer number (10510010601061).

Almost surely, 2^{21020021202121} is an apocalyptic number.

It is an amenable number.

21020021202121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020021202121 is an equidigital number, since it uses as much as digits as its factorization.

21020021202121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21020021202121 its reverse (12120212002012), we get a palindrome (33140233204133).

The spelling of 21020021202121 in words is "twenty-one trillion, twenty billion, twenty-one million, two hundred two thousand, one hundred twenty-one".