261550613 has 2 divisors, whose sum is σ = 261550614. Its totient is φ = 261550612.

The previous prime is 261550589. The next prime is 261550621. The reversal of 261550613 is 316055162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 259306609 + 2244004 = 16103^2 + 1498^2 .

It is a cyclic number.

It is not a de Polignac number, because 261550613 - 2²⁰ = 260502037 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261550643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130775306 + 130775307.

It is an arithmetic number, because the mean of its divisors is an integer number (130775307).

Almost surely, 2^261550613 is an apocalyptic number.

It is an amenable number.

261550613 is a deficient number, since it is larger than the sum of its proper divisors (1).

261550613 is an equidigital number, since it uses as much as digits as its factorization.

261550613 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5400, while the sum is 29.

The square root of 261550613 is about 16172.5264878435. The cubic root of 261550613 is about 639.5167356018.

The spelling of 261550613 in words is "two hundred sixty-one million, five hundred fifty thousand, six hundred thirteen".