261909687269 has 2 divisors, whose sum is σ = 261909687270. Its totient is φ = 261909687268.

The previous prime is 261909687251. The next prime is 261909687317. The reversal of 261909687269 is 962786909162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 170259390625 + 91650296644 = 412625^2 + 302738^2 .

It is a cyclic number.

It is not a de Polignac number, because 261909687269 - 2²⁴ = 261892910053 is a prime.

It is a super-2 number, since 2×261909687269² (a number of 24 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261909687769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130954843634 + 130954843635.

It is an arithmetic number, because the mean of its divisors is an integer number (130954843635).

Almost surely, 2^261909687269 is an apocalyptic number.

It is an amenable number.

261909687269 is a deficient number, since it is larger than the sum of its proper divisors (1).

261909687269 is an equidigital number, since it uses as much as digits as its factorization.

261909687269 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 35271936, while the sum is 65.

The spelling of 261909687269 in words is "two hundred sixty-one billion, nine hundred nine million, six hundred eighty-seven thousand, two hundred sixty-nine".