21021010121 has 2 divisors, whose sum is σ = 21021010122. Its totient is φ = 21021010120.

The previous prime is 21021010079. The next prime is 21021010123. The reversal of 21021010121 is 12101012012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20056224400 + 964785721 = 141620^2 + 31061^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21021010121 is a prime.

Together with 21021010123, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21021010123) 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, 10510505060 + 10510505061.

It is an arithmetic number, because the mean of its divisors is an integer number (10510505061).

Almost surely, 2^21021010121 is an apocalyptic number.

It is an amenable number.

21021010121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021010121 is an equidigital number, since it uses as much as digits as its factorization.

21021010121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21021010121 its reverse (12101012012), we get a palindrome (33122022133).

The spelling of 21021010121 in words is "twenty-one billion, twenty-one million, ten thousand, one hundred twenty-one".