21100210121 has 2 divisors, whose sum is σ = 21100210122. Its totient is φ = 21100210120.

The previous prime is 21100210073. The next prime is 21100210139. The reversal of 21100210121 is 12101200112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20754436096 + 345774025 = 144064^2 + 18595^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21100210121 is a prime.

It is not a weakly prime, because it can be changed into another prime (21100210721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550105060 + 10550105061.

It is an arithmetic number, because the mean of its divisors is an integer number (10550105061).

Almost surely, 2^21100210121 is an apocalyptic number.

It is an amenable number.

21100210121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100210121 is an equidigital number, since it uses as much as digits as its factorization.

21100210121 is an evil number, because the sum of its binary digits is even.

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

Adding to 21100210121 its reverse (12101200112), we get a palindrome (33201410233).

The spelling of 21100210121 in words is "twenty-one billion, one hundred million, two hundred ten thousand, one hundred twenty-one".