261644265 has 12 divisors (see below), whose sum is σ = 453516804. Its totient is φ = 139543584.

The previous prime is 261644261. The next prime is 261644281. The reversal of 261644265 is 562446162.

261644265 is a `hidden beast` number, since 2 + 6 + 1 + 644 + 2 + 6 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 150700176 + 110944089 = 12276^2 + 10533^2 .

It is not a de Polignac number, because 261644265 - 2² = 261644261 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261644261) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2907114 + ... + 2907203.

It is an arithmetic number, because the mean of its divisors is an integer number (37793067).

Almost surely, 2^261644265 is an apocalyptic number.

It is an amenable number.

261644265 is a deficient number, since it is larger than the sum of its proper divisors (191872539).

261644265 is a wasteful number, since it uses less digits than its factorization.

261644265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5814328 (or 5814325 counting only the distinct ones).

The product of its digits is 69120, while the sum is 36.

The square root of 261644265 is about 16175.4216328354. The cubic root of 261644265 is about 639.5930559153.

The spelling of 261644265 in words is "two hundred sixty-one million, six hundred forty-four thousand, two hundred sixty-five".