261564213601181 has 2 divisors, whose sum is σ = 261564213601182. Its totient is φ = 261564213601180.

The previous prime is 261564213601123. The next prime is 261564213601199. The reversal of 261564213601181 is 181106312465162.

261564213601181 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 138934170517156 + 122630043084025 = 11787034^2 + 11073845^2 .

It is a cyclic number.

It is not a de Polignac number, because 261564213601181 - 2¹⁴ = 261564213584797 is a prime.

It is a super-3 number, since 3×261564213601181³ (a number of 44 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261564213601081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130782106800590 + 130782106800591.

It is an arithmetic number, because the mean of its divisors is an integer number (130782106800591).

Almost surely, 2^{261564213601181} is an apocalyptic number.

It is an amenable number.

261564213601181 is a deficient number, since it is larger than the sum of its proper divisors (1).

261564213601181 is an equidigital number, since it uses as much as digits as its factorization.

261564213601181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 414720, while the sum is 47.

The spelling of 261564213601181 in words is "two hundred sixty-one trillion, five hundred sixty-four billion, two hundred thirteen million, six hundred one thousand, one hundred eighty-one".