261313249913 has 2 divisors, whose sum is σ = 261313249914. Its totient is φ = 261313249912.

The previous prime is 261313249877. The next prime is 261313249921. The reversal of 261313249913 is 319942313162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 250272073984 + 11041175929 = 500272^2 + 105077^2 .

It is a cyclic number.

It is not a de Polignac number, because 261313249913 - 2²⁶ = 261246141049 is a prime.

It is a super-2 number, since 2×261313249913² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (261313249933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130656624956 + 130656624957.

It is an arithmetic number, because the mean of its divisors is an integer number (130656624957).

Almost surely, 2^261313249913 is an apocalyptic number.

It is an amenable number.

261313249913 is a deficient number, since it is larger than the sum of its proper divisors (1).

261313249913 is an equidigital number, since it uses as much as digits as its factorization.

261313249913 is an evil number, because the sum of its binary digits is even.

The product of its digits is 209952, while the sum is 44.

The spelling of 261313249913 in words is "two hundred sixty-one billion, three hundred thirteen million, two hundred forty-nine thousand, nine hundred thirteen".