210121000120021 has 2 divisors, whose sum is σ = 210121000120022. Its totient is φ = 210121000120020.

The previous prime is 210121000120007. The next prime is 210121000120051. The reversal of 210121000120021 is 120021000121012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 157773445424100 + 52347554695921 = 12560790^2 + 7235161^2 .

It is a cyclic number.

It is not a de Polignac number, because 210121000120021 - 2³⁷ = 209983561166549 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 210121000119983 and 210121000120010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (210121000120001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105060500060010 + 105060500060011.

It is an arithmetic number, because the mean of its divisors is an integer number (105060500060011).

Almost surely, 2^{210121000120021} is an apocalyptic number.

It is an amenable number.

210121000120021 is a deficient number, since it is larger than the sum of its proper divisors (1).

210121000120021 is an equidigital number, since it uses as much as digits as its factorization.

210121000120021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 210121000120021 its reverse (120021000121012), we get a palindrome (330142000241033).

Subtracting from 210121000120021 its reverse (120021000121012), we obtain a palindrome (90099999999009).

The spelling of 210121000120021 in words is "two hundred ten trillion, one hundred twenty-one billion, one hundred twenty thousand, twenty-one".