21010122121 has 2 divisors, whose sum is σ = 21010122122. Its totient is φ = 21010122120.

The previous prime is 21010122079. The next prime is 21010122137. The reversal of 21010122121 is 12122101012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20665500025 + 344622096 = 143755^2 + 18564^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010122121 - 2³³ = 12420187529 is a prime.

It is not a weakly prime, because it can be changed into another prime (21010122181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505061060 + 10505061061.

It is an arithmetic number, because the mean of its divisors is an integer number (10505061061).

Almost surely, 2^21010122121 is an apocalyptic number.

It is an amenable number.

21010122121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010122121 is an equidigital number, since it uses as much as digits as its factorization.

21010122121 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 21010122121 its reverse (12122101012), we get a palindrome (33132223133).

The spelling of 21010122121 in words is "twenty-one billion, ten million, one hundred twenty-two thousand, one hundred twenty-one".