21010121161 has 2 divisors, whose sum is σ = 21010121162. Its totient is φ = 21010121160.

The previous prime is 21010121159. The next prime is 21010121183. The reversal of 21010121161 is 16112101012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19549352761 + 1460768400 = 139819^2 + 38220^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010121161 - 2¹ = 21010121159 is a prime.

Together with 21010121159, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21010121861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505060580 + 10505060581.

It is an arithmetic number, because the mean of its divisors is an integer number (10505060581).

Almost surely, 2^21010121161 is an apocalyptic number.

It is an amenable number.

21010121161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010121161 is an equidigital number, since it uses as much as digits as its factorization.

21010121161 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 16.

Adding to 21010121161 its reverse (16112101012), we get a palindrome (37122222173).

The spelling of 21010121161 in words is "twenty-one billion, ten million, one hundred twenty-one thousand, one hundred sixty-one".