261522500814821 has 2 divisors, whose sum is σ = 261522500814822. Its totient is φ = 261522500814820.

The previous prime is 261522500814803. The next prime is 261522500814871. The reversal of 261522500814821 is 128418005225162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 227264247981796 + 34258252833025 = 15075286^2 + 5853055^2 .

It is a cyclic number.

It is not a de Polignac number, because 261522500814821 - 2¹⁰ = 261522500813797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261522500814871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130761250407410 + 130761250407411.

It is an arithmetic number, because the mean of its divisors is an integer number (130761250407411).

Almost surely, 2^{261522500814821} is an apocalyptic number.

It is an amenable number.

261522500814821 is a deficient number, since it is larger than the sum of its proper divisors (1).

261522500814821 is an equidigital number, since it uses as much as digits as its factorization.

261522500814821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 614400, while the sum is 47.

The spelling of 261522500814821 in words is "two hundred sixty-one trillion, five hundred twenty-two billion, five hundred million, eight hundred fourteen thousand, eight hundred twenty-one".