21011302121 has 2 divisors, whose sum is σ = 21011302122. Its totient is φ = 21011302120.

The previous prime is 21011302097. The next prime is 21011302129. The reversal of 21011302121 is 12120311012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19582084096 + 1429218025 = 139936^2 + 37805^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011302121 - 2¹⁸ = 21011039977 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21011302096 and 21011302105.

It is not a weakly prime, because it can be changed into another prime (21011302129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505651060 + 10505651061.

It is an arithmetic number, because the mean of its divisors is an integer number (10505651061).

Almost surely, 2^21011302121 is an apocalyptic number.

It is an amenable number.

21011302121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011302121 is an equidigital number, since it uses as much as digits as its factorization.

21011302121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21011302121 its reverse (12120311012), we get a palindrome (33131613133).

The spelling of 21011302121 in words is "twenty-one billion, eleven million, three hundred two thousand, one hundred twenty-one".