21011343121 has 2 divisors, whose sum is σ = 21011343122. Its totient is φ = 21011343120.

The previous prime is 21011343109. The next prime is 21011343131. The reversal of 21011343121 is 12134311012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20720163025 + 291180096 = 143945^2 + 17064^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011343121 - 2²⁹ = 20474472209 is a prime.

It is not a weakly prime, because it can be changed into another prime (21011343131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505671560 + 10505671561.

It is an arithmetic number, because the mean of its divisors is an integer number (10505671561).

Almost surely, 2^21011343121 is an apocalyptic number.

It is an amenable number.

21011343121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011343121 is an equidigital number, since it uses as much as digits as its factorization.

21011343121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 19.

Adding to 21011343121 its reverse (12134311012), we get a palindrome (33145654133).

The spelling of 21011343121 in words is "twenty-one billion, eleven million, three hundred forty-three thousand, one hundred twenty-one".