261262336056221 has 2 divisors, whose sum is σ = 261262336056222. Its totient is φ = 261262336056220.

The previous prime is 261262336056133. The next prime is 261262336056287. The reversal of 261262336056221 is 122650633262162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 255198676053721 + 6063660002500 = 15974939^2 + 2462450^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261262336056221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261262336086221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130631168028110 + 130631168028111.

It is an arithmetic number, because the mean of its divisors is an integer number (130631168028111).

Almost surely, 2^{261262336056221} is an apocalyptic number.

It is an amenable number.

261262336056221 is a deficient number, since it is larger than the sum of its proper divisors (1).

261262336056221 is an equidigital number, since it uses as much as digits as its factorization.

261262336056221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1866240, while the sum is 47.

The spelling of 261262336056221 in words is "two hundred sixty-one trillion, two hundred sixty-two billion, three hundred thirty-six million, fifty-six thousand, two hundred twenty-one".