261939600939649 has 2 divisors, whose sum is σ = 261939600939650. Its totient is φ = 261939600939648.

The previous prime is 261939600939647. The next prime is 261939600939763. The reversal of 261939600939649 is 946939006939162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 219850841807424 + 42088759132225 = 14827368^2 + 6487585^2 .

It is a cyclic number.

It is not a de Polignac number, because 261939600939649 - 2¹ = 261939600939647 is a prime.

It is a super-2 number, since 2×261939600939649² (a number of 30 digits) contains 22 as substring.

Together with 261939600939647, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (261939600939647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130969800469824 + 130969800469825.

It is an arithmetic number, because the mean of its divisors is an integer number (130969800469825).

Almost surely, 2^{261939600939649} is an apocalyptic number.

It is an amenable number.

261939600939649 is a deficient number, since it is larger than the sum of its proper divisors (1).

261939600939649 is an equidigital number, since it uses as much as digits as its factorization.

261939600939649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 918330048, while the sum is 76.

The spelling of 261939600939649 in words is "two hundred sixty-one trillion, nine hundred thirty-nine billion, six hundred million, nine hundred thirty-nine thousand, six hundred forty-nine".