21013115161 has 2 divisors, whose sum is σ = 21013115162. Its totient is φ = 21013115160.

The previous prime is 21013115159. The next prime is 21013115173. The reversal of 21013115161 is 16151131012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20752131136 + 260984025 = 144056^2 + 16155^2 .

It is a cyclic number.

It is not a de Polignac number, because 21013115161 - 2¹ = 21013115159 is a prime.

Together with 21013115159, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21013116161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506557580 + 10506557581.

It is an arithmetic number, because the mean of its divisors is an integer number (10506557581).

Almost surely, 2^21013115161 is an apocalyptic number.

It is an amenable number.

21013115161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21013115161 is an equidigital number, since it uses as much as digits as its factorization.

21013115161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 180, while the sum is 22.

Adding to 21013115161 its reverse (16151131012), we get a palindrome (37164246173).

The spelling of 21013115161 in words is "twenty-one billion, thirteen million, one hundred fifteen thousand, one hundred sixty-one".