21122122261 has 2 divisors, whose sum is σ = 21122122262. Its totient is φ = 21122122260.

The previous prime is 21122122237. The next prime is 21122122303. The reversal of 21122122261 is 16222122112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17735580625 + 3386541636 = 133175^2 + 58194^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122122261 - 2²¹ = 21120025109 is a prime.

It is a super-2 number, since 2×21122122261² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21122122061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561061130 + 10561061131.

It is an arithmetic number, because the mean of its divisors is an integer number (10561061131).

Almost surely, 2^21122122261 is an apocalyptic number.

It is an amenable number.

21122122261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122122261 is an equidigital number, since it uses as much as digits as its factorization.

21122122261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 384, while the sum is 22.

Adding to 21122122261 its reverse (16222122112), we get a palindrome (37344244373).

The spelling of 21122122261 in words is "twenty-one billion, one hundred twenty-two million, one hundred twenty-two thousand, two hundred sixty-one".