21021200122121 has 2 divisors, whose sum is σ = 21021200122122. Its totient is φ = 21021200122120.

The previous prime is 21021200122079. The next prime is 21021200122129. The reversal of 21021200122121 is 12122100212012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17538632047225 + 3482568074896 = 4187915^2 + 1866164^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021200122121 - 2³⁴ = 21004020252937 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21021200122121.

It is not a weakly prime, because it can be changed into another prime (21021200122129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510600061060 + 10510600061061.

It is an arithmetic number, because the mean of its divisors is an integer number (10510600061061).

Almost surely, 2^{21021200122121} is an apocalyptic number.

It is an amenable number.

21021200122121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021200122121 is an equidigital number, since it uses as much as digits as its factorization.

21021200122121 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 17.

Adding to 21021200122121 its reverse (12122100212012), we get a palindrome (33143300334133).

The spelling of 21021200122121 in words is "twenty-one trillion, twenty-one billion, two hundred million, one hundred twenty-two thousand, one hundred twenty-one".