261304523565 has 16 divisors (see below), whose sum is σ = 418108765056. Its totient is φ = 139355236800.

The previous prime is 261304523527. The next prime is 261304523567. The reversal of 261304523565 is 565325403162.

It is a happy number.

It is not a de Polignac number, because 261304523565 - 2⁸ = 261304523309 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261304523567) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 140641 + ... + 736470.

It is an arithmetic number, because the mean of its divisors is an integer number (26131797816).

Almost surely, 2^261304523565 is an apocalyptic number.

It is an amenable number.

261304523565 is a deficient number, since it is larger than the sum of its proper divisors (156804241491).

261304523565 is a wasteful number, since it uses less digits than its factorization.

261304523565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 896980.

The product of its (nonzero) digits is 648000, while the sum is 42.

The spelling of 261304523565 in words is "two hundred sixty-one billion, three hundred four million, five hundred twenty-three thousand, five hundred sixty-five".