261645255 has 16 divisors (see below), whose sum is σ = 465147360. Its totient is φ = 139544064.

The previous prime is 261645229. The next prime is 261645289. The reversal of 261645255 is 552546162.

261645255 is a `hidden beast` number, since 2 + 6 + 1 + 645 + 2 + 5 + 5 = 666.

It is not a de Polignac number, because 261645255 - 2⁷ = 261645127 is a prime.

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 968922 + ... + 969191.

It is an arithmetic number, because the mean of its divisors is an integer number (29071710).

Almost surely, 2^261645255 is an apocalyptic number.

261645255 is a deficient number, since it is larger than the sum of its proper divisors (203502105).

261645255 is a wasteful number, since it uses less digits than its factorization.

261645255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1938127 (or 1938121 counting only the distinct ones).

The product of its digits is 72000, while the sum is 36.

The square root of 261645255 is about 16175.4522347908. The cubic root of 261645255 is about 639.5938626039.

The spelling of 261645255 in words is "two hundred sixty-one million, six hundred forty-five thousand, two hundred fifty-five".