21567563161 has 2 divisors, whose sum is σ = 21567563162. Its totient is φ = 21567563160.

The previous prime is 21567563141. The next prime is 21567563239. The reversal of 21567563161 is 16136576512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11754679561 + 9812883600 = 108419^2 + 99060^2 .

It is a cyclic number.

It is not a de Polignac number, because 21567563161 - 2¹³ = 21567554969 is a prime.

It is not a weakly prime, because it can be changed into another prime (21567563141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10783781580 + 10783781581.

It is an arithmetic number, because the mean of its divisors is an integer number (10783781581).

Almost surely, 2^21567563161 is an apocalyptic number.

It is an amenable number.

21567563161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21567563161 is an equidigital number, since it uses as much as digits as its factorization.

21567563161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 226800, while the sum is 43.

The spelling of 21567563161 in words is "twenty-one billion, five hundred sixty-seven million, five hundred sixty-three thousand, one hundred sixty-one".