261568665 has 24 divisors (see below), whose sum is σ = 453930048. Its totient is φ = 139335840.

The previous prime is 261568663. The next prime is 261568667. The reversal of 261568665 is 566865162.

It is a happy number.

261568665 is a `hidden beast` number, since 26 + 1 + 568 + 6 + 65 = 666.

It is an interprime number because it is at equal distance from previous prime (261568663) and next prime (261568667).

It is not a de Polignac number, because 261568665 - 2¹ = 261568663 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 261568665.

It is not an unprimeable number, because it can be changed into a prime (261568663) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 40510 + ... + 46520.

It is an arithmetic number, because the mean of its divisors is an integer number (18913752).

Almost surely, 2^261568665 is an apocalyptic number.

It is an amenable number.

261568665 is a deficient number, since it is larger than the sum of its proper divisors (192361383).

261568665 is a wasteful number, since it uses less digits than its factorization.

261568665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6989 (or 6986 counting only the distinct ones).

The product of its digits is 518400, while the sum is 45.

The square root of 261568665 is about 16173.0845851990. The cubic root of 261568665 is about 639.5314482297.

The spelling of 261568665 in words is "two hundred sixty-one million, five hundred sixty-eight thousand, six hundred sixty-five".