21115105013 has 2 divisors, whose sum is σ = 21115105014. Its totient is φ = 21115105012.

The previous prime is 21115105009. The next prime is 21115105021. The reversal of 21115105013 is 31050151112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13165956049 + 7949148964 = 114743^2 + 89158^2 .

It is a cyclic number.

It is not a de Polignac number, because 21115105013 - 2² = 21115105009 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21115108013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10557552506 + 10557552507.

It is an arithmetic number, because the mean of its divisors is an integer number (10557552507).

Almost surely, 2^21115105013 is an apocalyptic number.

It is an amenable number.

21115105013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21115105013 is an equidigital number, since it uses as much as digits as its factorization.

21115105013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 150, while the sum is 20.

Adding to 21115105013 its reverse (31050151112), we get a palindrome (52165256125).

The spelling of 21115105013 in words is "twenty-one billion, one hundred fifteen million, one hundred five thousand, thirteen".